The night sky this month

Northern Hemisphere

Ian Morison tells us what we can see in the Northern Hemisphere night sky during May 2018.

The Planets

• Jupiter - Jupiter reaches opposition on May 8th, so will be visible all night. It shines at magnitude -2.5 and has a disk some 44 arc seconds across throughout the month. Jupiter's equatorisl bands and sometimes the Great Red Spot (see 'highlights' for the times when it crosses Jupiter's central meridian) and up to four of its Gallilean moons will be visible in a small telescope. Sadly, lying in Libra during the month, Jupiter is heading towards the southern part of the ecliptic and will only have an elevation of ~20 degrees when crossing the meridian. Atmospheric dispersion will thus hinder our view and it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.
  
  
• Saturn - Saturn, now well into its new apparition, rises at around midnight on the first of May and a couple of hours earlier by month's end. With an angular size of ~17.5 arc seconds (increasing to 18.1 during the month) it climbs higher before dawn and so becomes easier to spot as the month progresses. Its brightness increases from +0.4 to +0.2 magnitudes during the month. The rings were at their widest some months ago and are still, at 25 degrees to the line of sight, well open and spanning ~2.5 times the size of Saturn's globe. Saturn, lying in Sagittarius, is close to the topmost star of the 'teapot'. It will been seen best just before dawn but, sadly, even when at opposition later in the year it will only reach an elevation of just over 15 degrees above the horizon when crossing the meridian. Atmospheric dispersion will thus greatly hinder our view and, as for Jupiter, it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.
  
  
• Mercury - Mercury reached greatest elongation east from the Sun on April 29th and might just be glimpsed low above the western horizon for the first few days of May, but for the remainder of the month will lie too close to the Sun to be visible.
  
  
• Mars - Mars starts the month in Sagittarius and moves into Capricornus in mid-May. Now a morning object, it rises at around 1:30 am BST at the start of the month and a little after midnight by May 31st. During the month, Mars has a magnitude which increases rapidly from -0.4 to -1.2 and has an angular size of 11.1 increasing to 15.1 arc seconds during the month so it should be possible to spot details, such as Syrtis Major, on its salmon-pink surface with a small telescope. It will only reach an elevation of ~10 degrees before dawn at the start of the month and ~131 degrees by month's end. Sadly, the atmosphere will hinder our view. Another reason for purchasing a ZWO Atmospheric Dispersion corrector?
  
  
• Venus - Venus, seen in the west after sunset, shines brightly at magnitude -3.9 all month with an angular size of 11.5 increasing to 13 arc seconds. Venus rises a little higher in the sky as April progresses, initially setting around two hours after the Sun but increasing to two and a half hours by month's end as its elevation at sunset stays at around 20 degrees - it will be very prominent in the evening sky. Venus starts the month in Taurus, not far above the Hyades Cluster, but passes into Gemini on the 19th before passing between the Hyades and Pleiades Clusters on the 27th.
  
  
Highlights
• May - a great month to view Jupiter. This is a great month to observe Jupiter which comes into opposition on May 8th and will be visible during all the hours of darkness. It is moving down the ecliptic and now lies in Libra and, sadly, will only reach an elevations of ~20 degrees when crossing the meridian. An interesting observation is that the Great Red Spot appears to be diminishing in size. At the beginning of the last century it spanned 40,000 km across but now appears to be only ~16,500 km across - less than half the size. It used to be said that 3 Earths could fit within it, but now it is only one. The shrinking rate appears to be accelerating and observations indicate that it is now reducing in size by ~580 miles per year. Will it eventually disappear?
  
  
• The features seen in the Jovian atmosphere have been changing quite significantly over the last few years - for a while the South Equatorial Belt vanished completely (as seen in Damian's image) but has now returned to its normal wide state.
  
  
• May: Look for the Great Red Spot on Jupiter. This list gives some of the best evening times during May to observe the Great Red Spot which should then lie on the central meridian of the planet. The times are in UT.
  
  
• May 5th and 6th before dawn: The Eta Aquarid Meteor Shower. The Eta Aquarids are one of the finest meteor showers that can be seen from the southern hemisphere but, in the northern hemisphere, may only be glimpsed in the pre-dawn sky in the south-east around 90 minutes before dawn. Sadly, this year the peak is when there is a waning gibbous Moon in the sky - so moonlight will hinder our view.
  
  
• May 5th - before dawn: Saturn, the Moon and Mars together in the southern sky. Before dawn on the 5th of May and given a clear sky and a low horizon to the east of south, you should be able to spot Saturn to the right of the waning gibbous Moon with Mars down to its lower left. Binoculars might be needed to penetrate the sky's pre-dawn brightness, but please do not use them after the Sun has risen.
  
  
• May 17th after sunset: Venus above a very thin crescent Moon. If clear after sunset on the 17th May and given a very low western horizon you should easily spot Venus! However it will be much harder to spot a very thin crescent Moon, just two days after new, down to its lower left. Binoculars may well be needed to see the Moon, but please do not use them until after the Sun has set.
  
  
• May 6th and 22nd - evenings: The Hyginus Rille. These evenings, should it be clear, are a superb time to view the Hyginus Crator and Rille as it will lie close to the terminator. For some time a debate raged as to whether the craters on the Moon were caused by impacts or volcanic activity. We now know that virtually all were caused by impact, but it is thought that the Hyginus crater that lies at the centre of the Hyginus Rille may well be volcanic in origin. It is an 11 km wide rimless pit - in contrast to impact craters which have raised rims - and its close association with the rille of the same name associates it with internal lunar events. It can quite easily be seen to be surrounded by dark material. It is thought that an explosive release of dust and gas created a vacant space below so that the overlying surface collapsed into it so forming the crater. The author's image of the crater and rille can be seen in the inset to the image of the 8 day old Moon below.
  
  

Gabriela Perez from the Carter Observatory in New Zealand speaks about the Southern Hemisphere night sky during May 2018.

• Introduction - Kia Ora, Gabriela Perez here from Wellington New Zealand. It's autumn here in the southern hemisphere and we can tell from the chilly night and fallen leaves but also from our skies. We can see the summer months sinking into the Western horizon with Orion and his companions making way for all our winter constellations. Quite a nice time year to see Orion and Scorpius on either sides of the sky knowing that they're doomed to chase one another forever.
  
  
• Orion - The best time to view the deep space objects will be around the middle of the month as new moon will be on the 15th of May and on the 29th we will round off the month with the full moon.
  
  
• The Planets - In the middle of May we will have sliver Venus setting 90 minutes after the Sun in the northwest once again becoming our evening star. The fainter planets, Saturn and Mars will also be in the sky in the constellation of Sagittarius.
  
  
• Scorpius - Another fantastic sight in the constellation of Scorpius is the Bug/Butterfly Nebula. It is a bipolar planetary nebula, having one the most complex structures ever seen with a star at its centre, also in its final stages but burning at some of the hottest temperatures recorded in the galaxy (for a star).
  
  
• Stellar Clusters - Between Scorpius and Sagittarius is the zone designated Sagittarius A and it is our galactic centre. The middle point of our Milky Way or the 'bulge' making up some of the brightest and star-rich regions of our night sky. We have noted some intense radio feedback form this zone as astronomers believe that in the centre of our galaxy (and in fact the centre of every galaxy) is a supermassive black hole holding it together. On a clear night you can follow the Milky Way up to the Crux constellation or the Southern Cross, the smallest constellation but arguably the most well-known in the South. Use the pointer stars, the reddish orange Alpha Centauri and the blue/white Beta Centauri to make sure you have the right cross shape in the sky. Nearby star clusters such as the Jewel Box cluster or the Southern Pleiades make for some stunning telescope observations. Pick out the different colours in the cluster depicting stars of different sizes and at different stages of their lives. For a little bit of a challenge, and for another look at a dying star, you can move towards the constellation of Carina and find Eta Carinae and the Carina Nebula.
  
  
• Meteor Shower - If you're up late enough, at about around midnight on the 6th till the early hours of the 7th of May you can catch the peak of the Eta Aquarids. This spectacular annual meteor shower is capable of producing up to 60 meteors per hour. They will radiate from Aquarius but can be seen in a lot of the night sky.
  
  
• Arcturus - And if you're up early enough soon after dusk Arcturus appears in the northeast, seen twinkling as it is close to the horizon with it's light being broken up. It is the brightest red object in the sky, only outshone by Mars and 120 times brighter than the Sun.
  
  
• That's all for me for this month in the South and remember to keep warm but not let that stop you from going outside and looking up!
  
  

Northern Hemisphere

Fiona Healy tells us what we can see in the Northern Hemisphere night sky during April 2018.

Fiona Healy and Fiona Healy from the Carter Observatory in New Zealand speak about the Southern Hemisphere night sky during April 2018.

We would have descriptions here, but unfortunately Fiona's cat has run off with them and none of us are brave enough to try and get them back.

Northern Hemisphere

Ian Morison tells us what we can see in the Northern Hemisphere night sky during March 2018.

Jupiter.Jupiter rises just before midnight at the beginning of the month and about one hour earlier by month's end. Initially it has a 39 arc second disk, shining at a magnitude of -2.2 but as the month progresses, its apparent diameter increases to 42.5 arc seconds and it brightens to magnitude -2.4. Jupiter will transit before dawn and so will enable the giant planet to be seen with the equatorial bands, sometimes the Great (but reducing in size) Red Spot and up to four of its Gallilean moons visible in a small telescope. Sadly, Jupiter, lying in Libra during the month, is heading towards the southern part of the ecliptic and will only have an elevation of ~20 degrees when crossing the meridian. Atmospheric dispersion will thus hinder our view and it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.

Saturn.Saturn, at the start of its new apparition, rises at around 3 am at the start of the month and just after 2 am at its end. With an angular size of ~16.3 arc seconds it climbs higher before dawn and so becomes easier to spot as the month progresses. Its brightness increases from +0.6 to +0.5 magnitudes during the month. The rings were at their widest a few months ago and are still, at 26 degrees to the line of sight, well open. Saturn, lying in Sagittarius, is just 3 degrees above the topmost star of the 'teapot'. Sadly, even when at opposition later in the year it will only reach an elevation of just over 15 degrees above the horizon when crossing the meridian. Atmospheric dispersion will thus greatly hinder our view and it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.

Mercury.Mercury gives us its best evening apparition this month when it reaches its peak height above the western horizon on March 15th when, at greatest elongation, it lies some 18 degrees west of the Sun. However, by this time its magnitude has dropped from -1.3 at the beginning of March to -0.4 magnitudes. Its magnitude continues to fall, dropping to +0.9 by 20th and soon after will be lost in the Sun's glare. Mercury flirts with Venus during the month as detailed in the highlights.

Mars.Mars starts the month moving quicky eastwards in Ophiuchus moving into Sagittarius on the 12th of the month as it moves towards Saturn. Now a morning object, it rises at around 2 am at the start of the month. During the month, Mars has a magnitude which increases from +0.8 to +0.3 and an angular size of just 7, increasing to 8.5, arc seconds so it will be hard to spot details on its salmon-pink surface. It will only reach an elevation of ~14 degrees before dawn at the start of the month and just 12 degrees by month's end.

Venus. Venus, seen low in the west after sunset shines at magnitude -3.9 all month with an angular size of ~10.3 arc seconds. Venus rises a little higher in the sky as March progresses, initially setting around one hour after the Sun but increasing to an hour and a half by month's end. It has two near conjunctions with Mercury as described in the highlights above.

Highlights

March 2nd to 4th after sunset: Venus and Mercury within 1.3 degrees of each other.After sunset on these three evenings and given a clear sky and a low western horizon, you should be able to spot Venus and Mercury. Their closest is on the 3rd when they are just 1.1 degrees apart. Binoculars might be needed to penetrate the skys residual brightness, but please do not use them until after the Sun has set. [Note: The sky brightness has been reduced in the chart.]

March 10th/11th before dawn: Saturn, Mars and a waning Moon. Mars below a waning Moon If clear before dawn on the 10th and 11th, looking just east of south, one should see a waning crescent Moon lying to the upper left of Mars on the 10th and Saturn on the 11th.

March 19th after sunset: Venus, Mercury and a very thin crescent Moon.Looking West after sunset on the 19th and given a very low western horizon, one might be able to spot Venus near Mercury which is close to maximum elongation from the Sun. A very thin crescent Moon, just two days after new, will be seen up to their left. Binoculars may well be needed, but please do not use them before the Sun has set. A tough observing challenge! [Note: the sky brightness has been reduced in the chart.]

March 23rd evening: The Moon in the Hyades Cluster.In the evening of the 23rd of the month, the Moon, coming towards first quarter, will lie within the Hyades cluster. After it has set from the UK it will occult Aldebaran which is a red giant star lying between our solar system and the cluster.

March 8th and 24th: The Alpine Valley.These are two good nights to observe an interesting feature on the Moon if you have a small telescope. Close to the limb is the Appenine mountain chain that marks the edge of Mare Imbrium. Towards the upper end you should see the cleft across them called the Alpine valley. It is about 7 miles wide and 79 miles long. As shown in the image is a thin rill runs along its length which is quite a challenge to observe. The dark crater Plato will also be visible nearby. You may also see the shadow cast by the mountain Mons Piton lying not far away in Mare Imbrium. This is a very interesting region of the Moon!

This month we welcome two new presenters, Gabriela Perez and Jasmine Chan-Hyams who tell us what we can see in the Southern Hemisphere night sky during March 2018.

Introduction.I'm Gaby, I work at Space Place at the Carter Observatory, in Wellington New Zealand as a telescope operator. I've been staring at the Southern Skies for most of my life. As a child I saw the fully mapped-out globe and I became fascinated with space, ever since I have wanted to explore the universe beyond. Now I bring the universe to me (mostly through collecting its light) with my eyes, a pair of binoculars or a telescope.

And I'm Jasmine, I am a PhD Biotech student at Victoria University of Wellington. But who I am is a scientist, a star-gazer and a story-teller. We wish a fond farewell to Claire who has contributed so much to this podcast over the years. Thank you for teaching me about treasuring that moment of awe when you share a wonder of the universe with someone who has never seen anything like it before. You will be sorely missed at Space Place and we wish you all the best in your new job!

Looking up into the night skies is one of the true delights of living in the southern hemisphere; especially here in Aotearoa, New Zealand where it is easy to get away from the bright city lights and where we a get a broader and brighter view of the Milky Way.

Early in the month of March we can look forward to gazing upon many star studded greek heroes and mythical creatures. We can use constellations as guideposts to find deep sky objects including beautiful nebulae and special features of our southern skies.

The region around Orion. Our journey begins with the Greek constellation Orion, who appears in the skies after full dark in north-north west for the month of March. For many of us finding the three bright stars that form Orion's belt were probably the first thing you could proudly identify as a child. These three stars are 2nd magnitude stars. You can also see with the naked eye Betelgeuse, located in Orion's armpit; a red supergiant hundreds of times larger than our sun. Yet the brightest star of this constellation is Rigel - a blue star at Orion's ankle. Blue stars are the hottest kind of stars you'll find in the night skies while red stars are cooler and burning up the last of their heat energy. Just below his belt you'll find the Orion Emission Nebula (M42)- a huge star forming cloud - more than two widths of our moon across, it lies about 1500 light years away. With the naked eye it appears as a diffuse cloudy patch. Through a telescope you can see the clouds of dust and gas, lit up by the baby stars they are forming.

From Orion's belt it's just a star jump to the right and up to find Sirius, the brightest star in our skies. Sirius is seriously bright at about 20 times brighter than our sun and is only 8.6 lya. Sirius is part of the Canis Major constellation - one of the two dog companions that accompany the hunter Orion. Below Canis Major you can look for the two stars that form Canis Minor. The star Procyon, in Canis Minor, forms a triangle with the 1st magnitude stars Sirius and Betelgeuse.

Within this "southern triangle" you can look for the Monoceros unicorn constellation - home to the gorgeous Rosette nebula. This nebula has a beautiful carnation pick colouring and can be seen with binoculars in the part of the constellation closest to Betelgeuse.

Neighboring Orion is the zodiac constellation Taurus the Bull. Taurus and his fiery eye, the red giant Aldebaran, can be found low in our Northern-Western sky after sunset where we can easily make out his V shaped horns. Near his shoulder lies the Pleiades star cluster. On a clear dark night you can see seven points of light with the naked eye but it is best viewed with a pair of binoculars. The Pleiades is a young cluster of mostly hot blue stars, the big ones that burn up all their fuel quickly -they live fast and die young. These bright blue stars are said to be seven beautiful sisters. You can find the seven sisters sheltering in the shoulder of the bull hiding from Orion's amorous intentions.

Crab Nebula.

After you get an eyeful of these blue beauties you can jump down to the Crab Nebula (M1) but you'll want a telescope for this part. M1 was the fist Messier object recorded by famous French astronomer Charles Messier in 1771. To find M1 with your telescope look for Aldebaran first then follow the bull's horn to the end, it will be close to the horizon. Large apertures are needed to make out the filamentous detail. The Crab Nebula is was first viewed more than a 1000 years ago, by ancient Chinese astronomers, who recorded a bright light forming in this area. They witnessed was a supernova - a dying star. At the heart of the Crab Nebula is the pulsar, the skeleton of the dying star. Although we cannot see it with a telescope we can listen to the radio waves it emits as it spins. We can listen to the song of supernova.

You can enjoy looking for Orion, his hunting dogs, Taurus and the unicorn Monoceros throughout the early evenings of March. Now I'll hand over to Gabriela who'll tell us what planets we can see this month and features of the skies to the south.

The Planets - But if you are looking for planets in March, you'll need stay up late. Venus sets shortly after the sun but becomes increasingly visible in our twilight skies towards the end of the month. Jupiter rises in the late evening about midnight in mid-March. This gas giant reflects the light of our sun and outshines Sirius, becoming the brightest object in our night sky after the Moon. For those early risers Mars and Saturn are in the eastern horizon just before dawn. Around the 7th of March the planets will line up quite nicely on either side of the waxing gibbous Moon. On the 21st of March we can observe the Autumn equinox when there night and day will be of equal length.

Constellations and Nebulae -

This is probably my favourite time of year to look at the Southern Skies because you can stay out late without either freezing to death or being eaten alive by mosquitoes and the most important objects stay high in the skies for longer. The Full Moon will occur mid-month on the 12th of March. So the beginning and end of March are excellent times to explore the deeper sky objects that you can only see from the southern hemisphere.

Turning to the south horizon we look for the kite shaped Southern Cross constellation Crux. The Crux will be low in our South Eastern sky in early March after sunset. We can use the pointer stars, red-orange Alpha Centauri and blue-white Beta Centauri to identify the true Southern Cross.

As night progresses, the Southern Cross journeys around the southern celestial pole, bringing with it the dark patches stretched out through our view of the Milky Way. Here these patched represents the Giant Moa -a now extinct large flightless bird native to New Zealand. These dark patches are where large interstellar objects, called Dark Nebulas, have blocked out the light from more distant stars - preventing their light reaching us here on Earth. Dark Nebulae are easily seen against the backdrop of the Milky Way as the large concentration of star-light surrounding them lets us see them better. The head of the Moa sits by the Crux, nearby Beta Cruxis and the Jewel Box Cluster. This dark nebula is usually known as the Coalsack nebula. Much like coal itself it could one day ignite as it becomes an active stellar nursery, shining up as one of the brightest sections of our skies.

Following the Moa's ascent, Scorpius rises in the east. In Maori starlore we know it as the legendary fish hook of Maui. Where the Milky Way bulges, next to Scorpius, is Sagittarius A - the Galactic Centre - where we have the brightest view of our own galaxy. From the Galactic Centre we receive intense radio feedback from the super-massive black hole at the centre of our Milky Way.

Using the Southern Cross we can find, Canopus, the second brightest true star in our sky. It is part of the Carina constellation, the keel of Argo Navis. The ship that used to dominate the night sky as the largest constellation. In March it is located above the Crux. In the centre of this constellation is the Great Carina Nebula which houses the giant red dying star Eta Carinae. It once illuminated our night sky as one of the brightest stars for a short period of time after it undertook a massive event known as an imposter supernova. Now this hardy star, encased in the Homunculus Nebula, has faded and can only be seen through a telescope.

The globular star cluster 47 Tucanae will be high in the sky and faintly spotted to the naked eye by the tenth brightest star, the pancake star Achernar (It's spinning so fast it's flattened itself out a bit). Globular clusters are fascinating things. Their structure allows us witness stellar interactions but also allows us to pinpoint the smallest and faintest stars. The large bright stars are at the core while the outer stars are fainter creating a unique and beautifully ordered structure found only in globular clusters.

Magellanic Clouds - We can also look for two of our neighbouring galaxies - the Magellanic Clouds. You can see them without the aid of a telescope. But you will need to get away from the bright city lights on a dark moonless night. These two small irregular dwarf galaxies orbit our Milky Way. The gravitational, pull of our galaxy, warps and distorts them - pulling away clouds of dust and gas and even stars to form the Magellanic Stream. The SMC and LMC are actually connecting by a bridge of neutral helium, suggesting they were once the same object. The Magellanic Clouds are the furthest objects away from home that we can see from our backyards in the southern hemisphere.

G - That's it for us in the month of March. Thanks for tuning in. J - and we wish you all very happy star gazing.

Northern Hemisphere

Ian Morison tells us what we can see in the Northern Hemisphere night sky during February 2018.

Jupiter - Jupiter rises around 2 am at the beginning of the month and just before midnight by month's end. Initially it has a 36 arcsecond disk, shining at a magnitude of -2 but as the month progresses, its apparent diameter increases to 39 arcseconds and it brightens to magnitude -2.2. Jupiter will transit before dawn and so will enable the giant planet to be seen with the equatorial bands, sometimes the Great (but reducing in size) Red Spot and up to four of its Gallilean moons visible in a small telescope. Sadly, Jupiter, lying in Libra during the month, is heading towards the southern part of the ecliptic and will only have an elevation of ~20 degrees when crossing the meridian. Atmospheric dispersion will thus hinder our view and it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.

Saturn - Saturn, at the start of its new apparition, rises at around 5 am at the start of the month and just after 3 am at its end. With an angular size of ~15.5 arc seconds it climbs higher before dawn and so becomes easier to spot as the month progresses. Its brightness remains at +0.6 magnitudes. The rings were at their widest a few months ago and are still, at 26 degrees to the line of sight, well open. Saturn, lying in Sagittarius, is just 3 degrees above the topmost star of the 'teapot'. Sadly, even when at opposition later in the year it will only reach an elevation of just over 15 degrees above the horizon when crossing the meridian. Atmospheric dispersion will thus greatly hinder our view and it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.

Mercury - Mercury passes through superior conjuction (between us and the Sun) on the 17th February so will be lost in the Sun's glare until the very end of the month when it might just be glimpsed after sunset with its ~5 arc second disk having an unusually bright magnitude of -1.5.

Mars - Mars starts the month moving quickly eastwards in Scorpius close to Beta Scorpii (Graffias) but moves into Ophiuchus on the 8th of the month. Now a morning object at the start of its new apparition, it rises four hours or so earlier than the Sun. During the month, Mars has a magnitude which increases from +1.2 to +0.8 and an angular size of just 5.6, increasing to 6.6, arc seconds so no details will be seen on its salmon-pink surface. It will only reach an elevation of ~14 degrees before dawn at the start of the month and just 12 degrees by month's end.

Venus - Venus passed through superior conjunction (on the far side of the Sun) on January 9th and so, at the beginning of February will be lost in the Sun's glare, setting less than half an hour after the Sun. However, by month's end, shining with a magnitude of -3.9, it will set around an hour after the Sun and its 10 arc second disk should be easy to spot 30 minutes or so after sunset. However a low western horizon will be needed as it will then only have an elevation of ~5 degrees some way to the south of west.

Highlights

February 8th before dawn: A waning Moon close to Jupiter - with Mars nearby. If clear before dawn on the 8th, a waning moon between Full Moon and Last Quarter lies close to Jupiter. Down to the left is Mars lying above Antares in Scorpius.

February 9th before dawn: Mars and a waning Moon. If clear before dawn on the 9th and looking to the South-southeast, Mars, at magnitude +1, will be seen to the lower right of a waning crescent Moon.

February 17th after sunset: Venus and a thin crescent Moon. Looking West-Southwest after sunset on the 17th and given a very low western horizon, one might be able to spot Venus at the start of its new evening apparition. A very thin crescent Moon, just two days after new, will be seen up to its left. Binoculars may well be needed, but please do not use them before the Sun has set. A very tough observing challenge!

February 23rd/24th evening: The Moon in a beautiful skyscape. In the evenings of the 23rb and 24th of the month, the Moon, coming towards first quarter, will pass through Taurus and Orion. On the 23rd, it will lie close to Aldebaran and on the 24th lie above Orion.

February 6th and 22nd evening: The Hyginus Rille. For some time a debate raged as to whether the craters on the Moon were caused by impacts or volcanic activity. We now know that virtually all were caused by impact, but it is thought that the Hyginus crater that lies at the centre of the Hyginus Rille may well be volcanic in origin. It is an 11 km wide rimless pit - in contrast to impact craters which have raised rims - and its close association with the rille of the same name associates it with internal lunar events. It can quite easily be seen to be surrounded by dark material. It is thought that an explosive release of dust and gas created a vacant space below so that the overlying surface collapsed into it so forming the crater.

In her final broadcast for the Jodcast, Claire Bretherton from the Carter Observatory in New Zealand tells us what we can see in the Southern Hemisphere night sky during February 2018.

Kia ora and welcome to the February Jodcast from Space Place at Carter Observatory in Wellington, New Zealand.

Lunar Eclipse - Whilst the Earth blocks all direct light from the Sun, some light passes though the Earth's atmosphere and is bent or refracted towards the surface of the Moon. Light with shorter wavelengths, towards the blue end of the spectrum, is scattered more strongly, so only the redder light gets through, giving the eclipsed moon a telltale reddish glow.

Partial Solar Eclipse - Whilst New Zealand won't see it, some parts of the southern hemisphere will also experience a partial solar eclipse this month, on the morning of the 16th NZ time. From parts of Chile and Argentina the moon will cover some 25% of the Sun's disk, whilst from Antarctica around 49% will be covered.

Orion - Orion is now high in the north after dark, with Sirius, or Takurua, the brightest star in our night-time sky, even higher.

Procyon - Below and to the right, and forming a triangle with Sirius and Betelgeuse, is Procyon, the brighter of the two main stars that form the constellation of Canis Minor, Orion's small hunting dog. Procyon is the eighth brightest star in the night-time sky and, like Sirius (at ~9 ly distant), is one of our Sun's nearest neighbours at just 11 light years away. Also like Sirius, it is in fact a binary system, with a 1.5 solar mass primary and a faint white dwarf companion.

Clusters and Nebulae - Just over a third of the way between Sirius and Procyon, in the constellation of Monoceros, is M50, a pretty, heart-shaped open cluster of stars, visible in binoculars.

Around a third of the way from Betelgeuse to Procyon is NGC2244, a rectangular cluster of stars that is embedded in a faint nebula called the Rosette. Whilst the cluster is visible in binoculars and small telescopes, the nebula is more of a challenge and is best seen in long exposure photographs.

Below Canis Minor sits another pair of stars, Castor and Pollux, marking the heads of Gemini, the twins. Pollux, the higher and brighter of the two stars, is the 17th brightest star in our night sky. It is about 35 light years away from us, whilst Castor is in fact a sextuple star system located 52 light years from Earth.

Nearby to Eta Geminorum, at the foot of the twin of Castor, is the open star cluster M35, covering an area almost the size of the full moon. Under good conditions it can be seen with the unaided eye as a hazy star, but binoculars or a wide-field telescope will reveal more detail and are the best ways to view this lovely cluster.

Next to Gemini is the faint zodiac constellation of Cancer, the crab. At the centre of Cancer is a lovely open cluster of stars known as M44, Praesepe (the Manger) or the Beehive. At magnitude 3.7, the cluster is visible to the naked eye as a hazy nebula, and has been know since ancient times. It was one of the first objects Galileo studied when he turned his telescope to the skies in 1609.

Galileo was able to pick out around 40 stars, but today we know that Praesepe contains over 1000 individual members, with a combined mass of between 500 and 600 times that of the Sun. As one of the closest open star clusters to our Solar System, M44 is a great target for binoculars or small telescopes, which will easily reveal a number of individual stars within it.

Higher, and to the east of Canis Major is Puppis, representing the Poop deck of the great ship Argo, which we explored last month. Inside Puppis are two lesser known Messier Objects, M46 and M47.

Messier 46 (also known as NGC 2437) is a rich open cluster at a distance of about 5,500 light-years away. M46 is estimated to contain around 500 stars, of which around 150 of magnitude 10-13. Estimated to be only 300 million years old, this is a young cluster, and a lovely sight in binoculars or a small telescope. Astronomer John Herschel described it in his General Catalogue of Nebulae and Clusters of Stars as “Remarkable, cluster, very bright, very rich, very large, involving a planetary nebula". This planetary nebula, located near the cluster's northern edge, is NGC 2438.

A planetary nebula is formed when a low or intermediate mass star comes to the end of its life, ejecting its outer layers into space as a glowing shell of ionized gas.

Located around 1 degree west is another open cluster, M47. The two fit easily within one binocular field of view, and are often referred to as sisters.

Messier 47 or NGC 2422 has actually been discovered several times. The first was some time before 1654 by Giovanni Batista Hodierna and then independently by Charles Messier on February 19, 1771. William Herschel also independently rediscovered it on February 4, 1785, and it was included as GC 1594 in John Herschel's General Catalogue of Nebulae and Clusters of Stars (the precursor to Dreyer's New General Catalogue) in 1864.

Due to a sign error by Messier, the cluster was considered a 'lost Messier Object' for many years, as no cluster could be found at the position of Messiers original coordinates. It wasn't until 1959 that Canadian astronomer T. F. Morris identified that the cluster was in fact NGC2422, and realized Messier's mistake.

M47 lies at a distance of around 1,600 light-years from Earth with an estimated age of about 78 million years. It is described as a course, bright cluster containing around 50 stars, scattered over an area around the same size as the full moon in the sky. It is bright enough to be glimpsed with the naked eye under good observing conditions, but best viewed with binoculars or a small telescope.

There are a couple of other excellent binocular targets in Puppis, including open cluster NGC2477 - a wonderful, rich cluster of over 300 stars, described by American Astronomer Robert Burnham as "probably the finest of the galactic clusters in Puppis" along with its neighbor NGC 2451, both located close to the second magnitude star Zeta Puppis.

Also known as Naos, this blue supergiant is one of the hottest, most luminous stars visible to the naked eye. It has a bolometric (total) luminosity of at least 500,000 times that of the Sun, but with most of its radiation emitted in the ultraviolet it is visually around 10,000 times brighter. It is also one of the closest stars of its kind to our Sun, at a distance of around 1,080 ly.

Planets - Our evening skies are still bereft of bright planets. Jupiter is the first to rise at around 1 am at the start of the month. Mars follows shortly afterwards, and the two are joined by Saturn around 3:30 am. You may spot Mercury briefly at the start of February, rising in the dawn twilight around an hour before the Sun, but it will soon disappear from view as it heads back towards the Sun. By months end Jupiter has moved into our evening skies, rising at 11 pm, Mars around 12:30 am and Saturn by 2 am, making a diagonal line down the eastern morning sky.

Farewell - After 8 years at Space Place at Carter Observatory, and being involved with the Jodcast for almost as long, I am moving on to a new role in February and so sadly this will be my last southern skies section. It's been a great pleasure bringing you a little taster of our wonderful New Zealand stars and some of the amazing stories within them over the past few years. I wish you clear skies and all the very best for the future. So farewell from me, Claire Bretherton, and the team here at space Place at Carter Observatory.

Northern Hemisphere

Ian Morison tells us what we can see in the northern hemisphere night sky during January 2018.

Jupiter. Jupiter is now a pre-dawn object rising some three and a half hours before the Sun at the beginning of the month with its 33 arc second disk, shining at a magnitude of -1.8, to be seen under clear skies. As the month progresses, its apparent diameter increases to 35.8 arc seconds and it brightens to magnitude -2. The elevation before dawn will then be sufficiently high to enable crisp views of the giant planet to be seen with the equatorial bands, sometimes the Great (but reducing in size) Red Spot and up to four of its Galilean moons visible in a small telescope.

Saturn. Saturn passed behind the Sun on December 21st (superior conjunction) on December 21st and reappears in the pre dawn sky this month at the start of its new apparition. It is unlikely to be seen in the first week of January, but climbs higher and so becomes easier to spot as the month progresses as its brightness increases to +0.6 magnitudes. The rings were at their widest a few months ago and are still well open.

Mercury. Mercury reaches greatest elongation west on New Year's Day shining at magnitude -0.3. It will be seen low in the Southeast before dawn and will be visible for a couple of weeks before sinking back towards the Sun. Its angular diameter reduces from 6.7 to 4.9 arc seconds but, as the percentage illuminated surface area increases from 62% to 95%, its brightness remains constant throughout the month.

Mars. At the start of the month Mars lies in Libra but moves down into Scorpius at the end of the Month. A morning object at the start of its new apparition, it rises four hours or so earlier than the Sun. During the month, Mars has a magnitude increasing from 1.5 to 1.2 and an angular size of just 4.8, increasing to 5.6, arc seconds so no details will be seen on its salmon-pink surface. Moving eastwards, Mars has a very close conjunction with Jupiter on the 6th of January.

Venus. Venus, passes through superior conjunction (on the far side of the Sun) on January 9th and so cannot be observed this month.

Highlights

Around the 17th of January (with no Moon in the sky): find M31 - The Andromeda Galaxy - and perhaps M33 in Triangulum Around new Moon (17th January) - and away from towns and cities - you may also be able to spot M33, the third largest galaxy after M31 and our own galaxy in our Local Group of galaxies. It is a face on spiral and its surface brightness is pretty low so a dark, transparent sky will be needed to spot it using binoculars (8x40 or, preferably, 10x50).

January 5th before dawn: A waning Moon closes on Regulus in Leo. If clear before dawn on the 5th, a waning Moon between Full Moon and Last Quarter lies just a few degrees from Regulus in Leo.

January 6th before dawn: Mars and Jupiter up close. If clear before dawn on the 6th and looking to the South-Southeast, Mars, at magnitude 1.4 will be seen just to the right of Jupiter shining at magnitude -1.8. At their closest they will be just 23 arc seconds apart.

January 13th before dawn: Saturn and Mercury. Looking Southeast before dawn on the 13th and given a very low eastern horizon, one might be able to spot Saturn at the start of its new apparition lying just above Mercury. A very thin crescent Moon will be seen up to their right. Binoculars may well be needed but please do not use them after the Sun has risen.

January 26th: Two Great Lunar Craters. This is a great night to observe two of the greatest craters on the Moon, Tycho and Copernicus, as the terminator is nearby.

Claire Bretherton from the Carter Observatory in New Zealand speaks about the southern hemisphere night sky during January 2018.

This month we will continue our tour of some of the clusters and nebulae along the Milky Way, which stretches across the eastern sky after dark, becoming brightest in the south towards the Southern Cross /Te Punga.

Orion still dominates our Eastern skies after dark. Just above and to the right of Sirius, at distance of around 4 degrees, is M41, or NGC 2287. M41 is an open cluster of stars, covering an area around the size of the full moon. It is just about visible as a blurry smudge to the naked eye from a clear, dark location. Through binoculars or a small telescope you will start to resolve a number of individual stars, showing hints of red and orange, including a prominent 6.3 magnitude K3 giant close to the cluster's centre.

Canopus. Canopus is the brightest star in the constellation of Carina, the keel, which along with Vela, the sails, and Puppis, the poop deck, once formed part of the southern constellation of Argo Navis. Straddling the Milky Way, this represented the great ship used by Jason and the Argonauts in their search for the Golden Fleece. The constellation was split into the three components used today by French Astronomer Nicolas Louis de Lacaille in 1763.

Eta Carina. Eta Carinae is now back to around 4th magnitude, but it is brightening again. It is expected to end its life in a huge supernova within the next few thousand years.

Nebulae in Eta Carinae. Also worth looking out for in Carina is NGC 2516, known as the southern beehive, located just above the false cross, and NGC 3532, the football cluster, or wishing well cluster. Both are visible to the naked eye, but a good pair of binoculars will reveal a stunning view. NGC 3532 in particular is a great target, a favourite of English astronomer John Herschel, and the very first object to be observed by the Hubble Space Telescope in May 1990. You'll find it roughly half way between Crux and the False Cross, close to Eta Carinae.

Planets. Mercury sits low in the morning twilight throughout most of January and is soon joined by Saturn, with the two sitting right next to each other on the morning of the 13th. Saturn continues to rise higher whilst Mercury, on its inner orbit, sinks back into the twilight.

Wishing you clear skies, and a very happy 2018, form the team here at Space Place at Carter Observatory.

Northern Hemisphere

Ian Morison tells us what we can see in the Northern Hemisphere night sky during December 2017.

The Planets

• Jupiter - Jupiter is now a pre-dawn object rising some 2 hours before the Sun at the beginning of the month with its 31 arc second disk, shining at a magnitude of -1.7, to be seen under clear skies. As the month progresses, its apparent diameter increases to 33 arc seconds and it brightens to magnitude -1.8. The low elevation will hinder our view, but the equatorial bands and up to four of its Gallilean moons should be visible.
  
  
• Saturn - Saturn will not be visible this month as it leaves the evening sky on its way to superior conjunction (passing behind the Sun) on December 21st before it reappears in the pre-dawn sky next year.
  
  
• Mercury - Mercury, just visible in the evening sky at the end of November, will not be seen for three weeks as it passes between the Earth and the Sun on December 13th (inferior conjunction). From the 20th or so it brightens rapidly in the pre-dawn sky to reach a magnitude of -0.3 by month's end when some 23 degrees away from the Sun. As the ecliptic makes quite a steep angle to the horizon, it will then have a reasonable elevation so making the end of the month an excellent time to observe Mercury. It will then have a magnitude of -0.3 and a disk 6.9 arc seconds across.
  
  
• Mars - As December begins, Mars lies in Virgo just 3 degrees up to the left of Spica, Alpha Virginis. Now a morning object at the start of its new apparition, it rises four hours or so earlier than the Sun. During the month, Mars has a magnitude increasing from 1.7 to 1.5 and an angular size of just 4.2 (increasing to 4.8) arc seconds so no details will be seen on its salmon-pink surface. Mars crosses from Virgo into Libra on the 21st, moving eastwards to closely approach Jupiter on New Year's Eve before a very close conjunction with it on the 7th of January.
  
  
• Venus - Venus, was seen in a close conjunction with Jupiter on the 13th November. Moving back towards the Sun, it rises just 45 minutes before the Sun at the start of December and is lost in the Sun's glare around the 12th of the month on its way towards superior conjunction (on the far side of the Sun) on January 9th. In its final week of visibility, it will have a magnitude of -3.9 and disk 9.9 arc seconds across.
  
  
Highlights
• M31 and M33. Around the 18th of December (with no Moon in the sky): find M31 - The Andromeda Galaxy - and perhaps M33 in Triangulum.
  
  
• December 2nd before dawn: Mars and Jupiter and a last chance to observe Venus for a while. If clear before dawn on the 2nd, there is a last chance for a while of spotting Venus as it sinks down to the Sun with, first, Jupiter and then Mars higher above in the southeastern sky. To spot Venus, a very low horizon will be needed and perhaps binoculars - but please to not use them after the Sun has risen.
  
  
• December 14th before dawn: Mars, Jupiter and a thin crescent Moon. If clear before dawn on the 14th, there will be a nice grouping of a very thin waning crescent Moon with Mars, to its upper right and Jupiter below.
  
  
• December 14th and 15th after midnight: the Geminid Meteor Shower. The early mornings of December 14th and 15th will give us the chance, if clear, of observing the peak of the Geminid meteor shower. Pleasingly, this is a great year to observe them as the thin waning crescent moon will not affect our view. The Geminids can often produce near-fireballs and so the shower is well worth observing if it is clear. An observing location well away from towns or cities will pay dividends. The relatively slow moving meteors arise from debris released from the asteroid 3200 Phaethon. This is unusual, as most meteor showers come from comets. The radiant - where the meteors appear to come from - is close to the bright star Castor in the constellation Gemini as shown on the chart. If it is clear it will be cold - so wrap up well, wear a woolly hat and have some hot drinks with you.
  
  
• December 22nd/23rd - late evenings: the Ursid Meteor Shower. The late evenings of the 22nd and 23rd of December are when the Ursid meteor shower will be at its best - though the peak rate of ~10-15 meteors per hour is not that great. Pleasingly, the Moon soon after new, will not affect our view during much of the night. The radiant lies close to the star Kochab in Ursa Minor (hence their name), so look northwards at a high elevation. Occasionally, there can be a far higher rate so it is worth having a look should it be clear.
  
  
• December 30/31st ~1 am: The Moon occults Aldebaran. Just after 1 am on the morning of the 31st of December, the near full Moon will occult the red giant star Aldebaran that lies between us and the Hyades cluster. It will disappear behind the dark limb of the Moon just after 1 am (but, due to parallax, the time is dependent on your location in the UK) and reappear just before 2 am.
  
  
• December 31st - before dawn: three planets in the Southeast. Before dawn on the 31st one will, if clear, be able to spot Jupiter and Mars close together in the pre-dawn sky with elusive Mercury above the horizon down to their lower left. A low horizon towards the Southeast will be needed to pick up Mercury and perhaps binoculars - but please do not use them after the Sun has risen.
  
  
• December 9th and 26th: The Alpine Valley. Two good evenings to observe the Alpine Valley.
  
  

Claire Bretherton from the Carter Observatory in New Zealand speaks about the Southern Hemisphere night sky during December 2017.

Kia Ora and welcome to the December Jodcast from Space Place at Carter Observatory in Wellington, New Zealand.

We're really noticing our days getting warmer now and our evenings getting brighter as we head towards the southern hemisphere summer solstice on the 22nd of December. The eastern evening sky is dominated by our summer constellations of Taurus and Orion, with his two dogs Canis Major and Canis Minor.

• The summer Milky Way stretches through these constellations and along our southern horizon. Whilst not as bright as our winter Milky Way, we can still pick out the mottled glow of bright and dark regions when observed from a dark location. The bright regions are the combined light of the many distant stars that form our galaxy, whilst the dark patches are clouds of interstellar gas and dust that block the light from more distant stars. Throughout this region there are many star clusters and nebulae that can be observed with binoculars and small telescopes, and some that can even be seen with the naked eye.
  
  
• Orion - We'll start our tour of the southern skies in Orion, sitting high in the east after dark, and easy to find by the three bright stars that form his belt. Here in Aotearoa we call these Tautoru, meaning line of three. As he lies along the celestial equator, Orion can be seen (at least partially) throughout the world. Above Orion's belt is a line of faint stars which form Orion's sword, but in New Zealand we see him upside down, so instead his belt and sword become a pot or saucepan.
  
  

In Greek mythology Orion is a hunter, and the arch enemy of Scorpius, our winter constellation. The two continually chase each other around the sky. Just as one rises in the east, the other sets below the western horizon.

At the top left of the constellation is the bright blue-white supergiant Rigel or Puanga. Whilst Rigel has been given the Beta designation, it is, in fact, normally the brightest star in the constellation and the seventh brightest in the night sky. Its colour tells us that it is extremely hot, with over twice the temperature and many tens of thousands of times the luminosity of the Sun. With an estimated age of just 8 million years, compared to 4.5 billion years for the Sun, Rigel is a young star, but has already used up all the hydrogen in its core and has swollen out to between 79 and 115 times the Sun's radius. Hot, massive, blue stars like Rigel don't live very long, they live fast and die young, using their fuel quickly before meeting a violent death. Over the next few million years Rigel will expand further and cool to become a red supergiant before ending its life in a massive explosion called a supernova.

• Betelguese

  At the bottom right of Orion is Betelguese, a star that has already reached the red supergiant phase, bloating out and cooling down to give it its wonderful red hue.

  Betelgeuse is designated Alpha Orionis, but is currently the second brightest star in the constellation. Estimates of its mass range from around 8 to 20 times that of the Sun, and if it were placed at the centre of the Solar System its surface would reach out almost as far as the orbit of Jupiter.

  One day soon Betelgeuse is also going to end its life in a supernova. Of course, soon to astronomers could be a million years, but if it does go bang within our lifetimes it is sure to be a spectacular sight, perhaps becoming so bright you could see it in the daytime. At a distance of over 600 light years, it is possible that this explosion has already happened and we are just waiting for the light to reach us.
  
  

But, as well as stars at the end of their lives, Orion also contains stars whose lives are just beginning. If you look carefully you may see the middle star of Orion's sword has a fuzzy appearance. This is the great nebula in Orion, or M42. The Orion Nebula is a stellar nursery, a huge cloud of gas and dust in which new stars are being born. At around 1,344 light years away, M42 is the closest massive star formation region to the Earth, with around 700 stars in various stages of the star formation process. In the heart of the Orion nebula is a small group of bright stars known as the Trapezium Cluster. The ultraviolet radiation from these stars is lighting up the surrounding gas.

Whilst easily spotted with the naked eye, through binoculars or a small telescope the nebula is a wonderful sight. Take your time and you should be able to clearly see some of the nebulosity of M42 and the bright star cluster that lights it up.

Another nebula in Orion that is well worth a look is the reflection nebula M78, easily found as a hazy patch in a small telescope. With a larger telescope the famous Horsehead nebula, silhouetted against the emission nebula IC434, is a lovely sight just to the south of the star Alnitak, the easternmost star in Orion's belt. Its proximity to bright Alnitak makes viewing the horsehead nebula more challenging, but long exposure photographs will reveal much more detail.

• Aldebaran - Following Orion's belt to the left we come to an upturned V shape of stars marking the head of Taurus the bull. At the bottom of this V is the bright orange star Aldebaran, at around 65ly away, representing the eye of the bull. The other stars in the V are part of the more distant Hyades cluster. At 153 ly away, the Hyades is the closest, and one of the best studied, open clusters to Earth. It is estimated to be around 625 million years old. Over time the cluster will continue to spread out and disperse into space, with some of the largest and brightest members already coming towards the ends of their lives.
  
  
• Crab Nebula - Near to the fainter of the two horns of Taurus, and just about visible in binoculars under excellent conditions, is the Crab Nebula. First discovered by English astronomer John Bevis in 1731, the Crab Nebula is a supernova remnant now believed to be associated with Supernova SN1054, observed and recorded by Chinese astronomers in 1054 AD.
  
  
• Pleiades - Continuing further around the sky you come to another famous open cluster, the Pleiades, or M45, at a distance of 444ly away. This group of stars is even younger than the Hyades, and is dominated by a number of hot, massive, blue stars only around 100 million years old. The Pleiades has many different names in many different cultures, but here in New Zealand is known as Matariki, meaning little eyes, or eyes of God. The rising of this group of stars for the first time before the Sun, around June, each year marks the coming of the Māori New Year.
  
  
• Sirius - Following Orion's belt to the right you come to Sirius, or Takurua, the brightest star in our nighttime sky, and in the constellation of Canis Major, Orion's large hunting dog. Canis Minor, the small dog, is a little below, close to the eastern horizon. It contains just two bright stars, and looks like a single line when traced on the sky. Here at Space Place we like to call it the hotdog constellation, as that's the only dog we know of with no head, no legs and no tail. The brighter of the two stars, Procyon, is one of the Sun's nearest stellar neighbours at just 11.46 light years away. Whilst it appears as a single star, the eighth brightest in the night sky, it is actually a binary star system, consisting of a white main-sequence star and a faint white dwarf companion.
  
  
• Crux - From Orion and his hunting dogs you can follow the band of the Milky Way around the sky, through the False and Diamond Crosses to Crux, the Southern Cross, low in the south. Scanning a pair of binoculars along the Milky Way should pick out glowing gas clouds and numerous star clusters whilst revealing much more detail than the eye can see.
  
  
• Planets - Both Mercury and Saturn quickly disappear from our dusk skies this month as they move closer to the Sun, leaving our evenings bereft of bright planets. Mars is the first to rise, around 3:30 am at the start of the month, with Jupiter joining it around 40 minutes later. By the end of December Mecury will also reappear in the morning, rising rapidly up the dawn sky to sit just below orange Antares.
  
  
• We also have a number of meteor showers happening this month. The Phoenicids reach their peak on 6th December and are thought to be associated with the comet D/1819 W1 (Blanpain). With the radiant in the constellation of Phoenix, not far from Achernar, this shower is well placed for southern hemisphere observers throughout the hours of darkness. The Pheonicids were first discovered during an outburst in 1956, where approximately 100 meteors an hour were seen from locations across the southern hemisphere. However, activity is very uncertain, and rates since have been much much lower than this. The minor Puppid-Velids meteor shower also reaches its peak at around the same time with a zenithal hourly rate of around 10, however , the radiant will only rise around 14 degrees above out horizon, so we may only get around 3 an hour.
  
  
• Just a few days later, peaking on the 15th of the month, are the Geminids. The Geminids are one of the best meteor showers of the year, but we are not well placed for viewing in New Zealand, with the radiant in the constellation of Gemini and well north of the equator. The constellation is at its highest around 3 am, but still appears low in our northern sky. Due to this low height we only see around half of the meteors visible to those in the northern hemisphere.
  
  

Wishing you clear skies and a Merry Christmas from the team here at Space Place at Carter Observatory.

Northern Hemisphere

Ian Morison tells us what we can see in the Northern Hemisphere night sky during November 2017.

The Planets

• Jupiter

  Jupiter passed behind the Sun on October 26th and so will become visible again in the pre-dawn sky after the first week or so November. It will then lie down to the lower left of Venus. However, by the end of November it will rise some two hours before the Sun allowing its 31 arcsecond disk, shining at a magnitude of -1.7, to be observed under clear skies. The low elevation will, of course, hinder our view.

• Saturn

  Saturn can be seen low in the southwest during twilight this month dropping down towards the horizon a little more each week. Shining at magnitude +0.5, it sets around 2 hours after the Sun on the 1st but little more than one hour by month end. It starts the month moving slowly eastwards in Ophiuchus but reaches the boundary of Sagittarius on the 18th. Last month, Saturn's rings reached their maximum tilt to the line of sight of 27 degrees and it is a real pity that Saturn is so low in the sky. Sadly, this will not improve for quite a few years as Saturn moves slowly through the lowest part of the ecliptic. Towards the end of the month Saturn edges closer to Mercury, but with both so low above the horizon after sunset, will be difficult to spot.

• Mercury

  Mercury passed between us and the Sun (Superior conjunction) on October 8th and will become visible again after sunset in the latter part of the month. From around the 17th, it might be glimpsed with binoculars low in the southwest 20 minutes after sunset shining at magnitude -0.4. It reaches greatest elongation, 22 degrees east of the Sun on November 23rd but, due to the shallow angle of the ecliptic to the horizon, never lies far above the horizon. In the last few days of the month its magnitude falls to -0.2 and it only lies ~5 degrees above the horizon 30 minutes after sunset.

• Mars

  Mars, lying in Virgo, has now become a morning object at the start of its new apparition and rises three to four hours earlier than the Sun. During the month, Mars has a magnitude of 1.7 and an angular size of just 3.9 (increasing to 4.2) arc seconds so no details will be seen on its salmon-pink surface. On the 4th, Mars is just three degrees to the upper right of Porrima, Gamma Virginis. This closes to two degrees by the 6th whilst, at the end of the month, it will lie just 3 degrees to the upper left of Spica, Alpha Virginis.

• Venus

  Venus, now moving back towards the Sun, rises some 90 minutes before dawn at the start of the month but this falls to 45 minutes by month's end. Its magnitude remains at -3.9 during the month as its angular diameter shrinks from 10.4 to 10 arc seconds. However, at the same time, its illuminated phase increases from 96% to 99% - which explains why its magnitude does not change. At the beginning of the month, it lies close to Spica, Alpha Virginis, with Venus some 100 times (5 magnitudes) brighter than Spica. By month's end, binoculars might be needed to spot it low above the eastern horizon. But please do not use them after the Sun has risen.

  HIGHLIGHTS
• November - a good month to observe Neptune and Uranus with a small telescope.

  Neptune came into opposition - when it is nearest the Earth - on the 2nd of September, so will be well placed to spot this month. Its magnitude is +7.9 so Neptune, with a disk just 3.7 arc seconds across, is easily spotted in binoculars lying in the constellation Aquarius as shown on the charts. It rises to an elevation of ~27 degrees when due south. Given a telescope of 8 inches or greater aperture and a dark transparent night it should even be possible to spot its moon Triton. Uranus reached opposition on October 19th and so is visible all night. It will be highest in the sky in the south around 1 am BST shining at magnitude 5.7 and with a disk 3.7 arc seconds across. It lies in Pisces, one degree and 18 arc minutes up to the right of Omicron Pisces as shown in the accompanying chart. Its turquoise green colour should be seen in a small telescope and it will be easily spotted in binoculars.

• Around the 18th of November (with no Moon in the sky): find M31 - The Andromeda Galaxy - and perhaps M33 in Triangulum

  In the evening, the galaxy M31 in Andromeda is visible in the south. The chart provides two ways of finding it:

  1. Find the square of Pegasus. Start at the top left star of the square - Alpha Andromedae - and move two stars to the left and up a bit. Then turn 90 degrees to the right, move up to one reasonably bright star and continue a similar distance in the same direction. You should easily spot M31 with binoculars and, if there is a dark sky, you can even see it with your unaided eye. The photons that are falling on your retina left Andromeda well over two million years ago!
  2. You can also find M31 by following the "arrow" made by the three rightmost bright stars of Cassiopeia down to the lower right as shown on the chart.

  Around new Moon (18th November) - and away from towns and cities - you may also be able to spot M33, the third largest galaxy after M31 and our own galaxy in our Local Group of galaxies. It is a face on spiral and its surface brightness is pretty low so a dark, transparent sky will be needed to spot it using binoculars (8x40 or, preferably, 10x50). Follow the two stars back from M31 and continue in the same direction sweeping slowly as you go. It looks like a piece of tissue paper stuck on the sky just a bit brighter than the sky background. Good Hunting.

• November early mornings: November Meteors.

  In the hours before dawn, November gives us a chance to observe meteors from two showers. The first that it is thought might produce some bright events is the Northern Taurids shower which has a broad peak of around 10 days but normally gives relatively few meteors per hour. The peak is around the 10th of November but then the Moon is close to third quarter so its light will intrude. The meteors arise from comet 2P/Encke. Its tail is especially rich in large particles and, this year, we may pass through a relatively rich band so it is possible that a number of fireballs might be observed!

  The better known November shower is the Leonids which peak on the night of the 17th/18th of the month. Happily, the Moon is new so will not hinder our view. As one might expect, the shower's radiant lies within the sickle of Leo and meteors could be spotted from the 15th to the 20th of the month. The Leonids enter the atmosphere at ~71 km/sec and this makes them somewhat challenging to photograph but it is worth trying as one might just capture a bright fireball. Up to 15 meteors an hour could be observed if near the zenith. The Leonids are famous because every 33 years a meteor storm might be observed when the parent comet, 55P/Temple-Tuttle passes close to the Sun. In 1999, 3,000 meteors were observed per hour but we are now halfway between these impressive events hence with a far lower expected rate.

• November late night: Comet 2107 O1 (ASASSN).

  Throughout November, with binoculars or a small telescope, it should be possible to spot Comet 2107 O1 (ASASSN) as it nears the Pole Star. It was discovered in July by the 'All Sky Automated Survey for Supernovae' and brightened rapidly. Its brightness is now falling but, at magnitude +8 or +9, should be visible near the Pole Star this month.

• November 6th - very early morning: The Moon occults Aldebaran and the Hyades Cluster

  In the early hours of the 6th November, a near full Moon, passing across the Hyades Cluster (at a distance of 153 light years) will occult the red giant star Aldebaran which lies at a distance of 65 light years in front of the Hyades Cluster.

• November 15th - 1 hour before dawn: Mars and a crescent Moon

  In the hour or so before dawn, Mars will be seen to the right of a thin Crescent Moon.

• November 16th - before dawn: three planets and a crescent Moon

  Just before dawn, Mars, a very thin Crescent Moon, Jupiter and Venus will form a lineup along the ecliptic. In the dawn glare, binoculars and a very low eastern horizon will be needed to spot them all but please do not use the binoculars after the Sun has risen.

  Claire Bretherton from the Carter Observatory in New Zealand speaks about the Southern Hemisphere night sky during November 2017.

  Kia ora and welcome to the November Jodcast from Space Place at Carter Observatory in Wellington, New Zealand.

  The Planets

  Mercury now joins Saturn in our western evening skies. Unfortunately it won't be as easy to spot as its last evening appearance in July-August, as it sets before twilight ends. At the start of the month orange Antares, the brightest star in Scorpius or Te Matau a Maui, will sit between the two planets, but as the stars and Saturn slowly sink closer to the horizon from night to night Mercury climbs higher, sitting level with Antares on the 14th and with Saturn on the 24th, when it also reaches its greatest elongation east.

  Constellations

  Scorpius/Te Matau a Maui has been dominating our evening skies over the winter months, but is now disappearing from view, ready to reappear in the morning over the coming months. As Scorpius sets in the west, his arch enemy, and our summer constellation, Orion rises towards the east along with Taurus and Canis Major. Antares, which marks the heart of the Scorpion, is also known as Rehua to Maori. It represents one of the four Pou, or pillars, that hold Ranginui, the sky father up in the sky. It sits just above the south western horizon at around 11pm at the beginning of the month. These four pou form the basis of a celestial compass, a map of the night sky that was used to navigate the vast pacific oceans and bring our Polynesian ancestors to Aotearoa/New Zealand.

  The other three pou are marked by Matariki (the Pleiades), Tautoru (the belt of Orion) and Takurua (Sirius), which line up along the eastern horizon. Matariki supports one of Rangi's shoulders and marks the rising point of the Sun at the winter solstice. Takurua (Sirius) supports the other shoulder and is the closest bright star to the Sun's rising point at the summer solstice. These two stars represent the extent of the Sun's movement throughout the year. In between, rising directly east, is Tautoru, or the belt of Orion, marking the rising point of the Sun at the time of the equinox.

  Stretching from Scorpius around to Orion is Te Waka o Tamareriti, or Tamarereti's canoe, which lines up along the southern horizon in our evening sky. The front of the canoe is marked by the tail of Scorpius, with the sting representing the beautifully carved wood that adorns the prow. The star at the end of the Scorpion's curving tail marks the place where the bow meets the water, whilst Rehua or Antares, marks the crest of a wave as the great waka glides through the waters of the Milky Way.

  The Southern cross marks the anchor, Te Punga and the pointers Alpha and Beta Centauri are the anchor line, Te Taura.

  Orion marks the stern of the canoe, with the elaborately carved stern post rising all the way up from red Betelgeuse to bluish Rigel. A tall mast rises from the waka all the way to Achernar, high in the south, the brightest star in the southern constellation of Eridanus, the river, which we explored last month. A little below Achernar, the two small fuzzy patches of light that make up the Large and Small Magellanic Clouds mark the waka\92s sails.

  • Mythology

    One story tells of Tamarereti sailing across the sky in his waka with all the stars in kete or baskets. He places the key seasonal and navigational stars in their correct positions in the sky, but he finds he has lots of smaller stars left over. So he capsizes his waka spilling all the smaller stars into the sky forming Te Ika Roa, or the Milky Way. Another story tells of Tamareriti scattering bright pebbles in the dark, lightless sky to help guide his way home. The pebbles became the stars and the wake of his waka formed the Milky Way. The sky we see in the mid-evening in October/November each year is, in fact, the same sky we see just before sunrise around June, the time we celebrate Matariki, or Maori New Year. It is said that the bright star Canopus, or Atutahi (the ariki or high chief of the heavens), pulls up the anchor at the start of the year starting the waka in motion. During the year you can track the progress of Tamarereti's waka as it moves across the sky, one day at a time.

  • Pegasus

    On the opposite side of the sky is the Great Square of Pegasus, the flying horse, leaping over the northern horizon. Last month we talked a little about this wonderful constellation, its brightest star Enif, marking the horse's muzzle, and the beautiful globular cluster, M15. But we can also use Pegasus to help us find some of our nearest galactic neighbours.

  • Alpheratz and M31

    The star at the bottom right of the Great Square of Pegasus is in fact Alpha Andromodae, or Alpheratz, the brightest star in the constellation of Andromeda. Located some 97 light years from Earth it is a spectroscopic binary star whose two components orbit each other in just 100 days. M31 is approaching the Milky Way at 110 km/s and is expected to collide and merge with our own Galaxy in around 4 billion years.

  • M33

    A little higher and towards the east, the Triangulum galaxy or M33 is better placed in our skies. At around 3 million light years from Earth and shining at magnitude 5.7 it is just at the limit of naked eye visibility under excellent conditions, making it one of the most distant objects able to be glimpsed unaided. To find M33, head back from Andromeda towards Mirach and then continue a similar distance to the other side. Whilst spotting it with the naked eye is a real challenge, it is easily observable in a pair of binoculars. With the mass of 10s of billions of Suns, M33 is also approaching us, at around 100,000 kilometres per hour. The most striking feature of the Triangulum Galaxy is a massive region of star formation, known as NGC604, which can be seen with a small telescope. NGC604 is 100 times larger than the Orion Nebula and contains over 200 hot, massive blue stars formed just 3 million years ago. In fact, if it were at the same distance as the Orion Nebula, it would be second brightest to only the Moon in the night time sky.

  • Leonids Meteor Shower

    Look out for the Leonid meteor shower, which peaks around the 17th -18thof the month, when the Earth passes through the trail of dust and debris left behind by the comet Temple-Tuttle. Whilst normally a reliable but fairly quiet meteor shower, observers have noticed that roughly every 33 years the number of meteors observed during the shower shows a marked increase as the Earth passes through the denser parts of the cometary debris trail. The radiant of the shower, from which the meteors appear to originate, is located in the constellation of Leo, which rises only a couple of hours before the Sun in our morning sky. The best time to observe the Leonids is about 2-3 hours before sunrise on the mornings around the peak. Look around 20 degrees away from the radiant point for the best chance of meteor spotting.

  Wishing you clear skies from the team here at Space Place at Carter Observatory.

Northern Hemisphere

Ian Morison tells us what we can see in the northern hemisphere night sky during October 2017.

The Planets

• Jupiter

  Jupiter might just be visible for the first few days of October very low above the west-southwestern horizon after sunset. It passes behind the Sun on October 26th to become visible again in the pre-dawn sky in mid November.

• Saturn

  Saturn can be seen low in the southwest during twilight this month dropping down towards the horizon a little more each week. Shining at magnitude +0.5, it sets around 3 hours after the Sun on the 1st but nearer 2 hours by month end. It is moving slowly eastwards in Ophiuchus moving closer to the boundary of Sagittarius which it will reach on the 18th of November. This month, Saturn's rings reach their maximum tilt to the line of sight of 27 degrees and it is a real pity that Saturn is so low in the sky. Sadly, this will not improve for quite a few years as Saturn moves slowly through the lowest part of the ecliptic.

• Mercury

  Mercury passes between us and the Sun (Superior conjunction) on October 8th so will not be visible this month.

• Mars

  Mars has now become a morning object at the start of its new apparition. Initially lying in Leo, it moves into Virgo on the 12th of the month and is still not easily seen in the pre-dawn sky. During the month, Mars has a magnitude of 1.8 and an angular size of just 3.7 (increasing to 3.9) arc seconds so no details will be seen on its salmon-pink surface. As the month progresses Mars rises higher in the sky before dawn and, as described in the highlights, flirts with Venus at the beginning of the month.

• Venus

  Venus, now moving back towards the Sun, is visible in the east before dawn this month, rising around 2 hours before sunrise at the start of the month and close to Mars. Its magnitude remains at -3.9 during the month as its angular diameter shrinks from 11.2 to 10.6 arc seconds. However, at the same time, its illuminated phase increases from 91% to 96% - which explains why its magnitude does not change. By month's end, Venus rises just an hour and a half before the Sun and binoculars might be needed to spot it low above the eastern horizon. But please do not use them after the Sun has risen.

  HIGHLIGHTS
• October - a good month to observe Neptune and Uranus with a small telescope.

  Neptune came into opposition - when it is nearest the Earth - on the 2nd of September, so will be well placed to spot this month. Its magnitude is +7.9 so Neptune, with a disk just 3.7 arc seconds across, is easily spotted in binoculars lying in the constellation Aquarius as shown on the charts. It rises to an elevation of ~27 degrees when due south. Given a telescope of 8 inches or greater aperture and a dark transparent night it should even be possible to spot its moon Triton. Uranus reaches opposition (when it is nearest the Earth) on October 19th and so is visible all night. It will be highest in the sky in the south around 1 am BST shining at magnitude 5.7 and with a disk 3.7 arc seconds across. It lies in Pisces, one degree and 18 arc minutes up to the right of Omicron Pisces as shown in the accompanying chart. Its turquoise green colour should be seen in a small telescope and it will be easily spotted in binoculars.

• October 5th - before dawn: Venus and Mars close in the East.

  Before dawn on the 5th, Venus and Mars will lie just a quarter of a degree apart in the eastern sky.

• October 1st- 14th - evening: Saturn in the Southwest

  After dark in the evenings of the first part of the month we will have our last good views of Saturn this apparition. Its rings are at their widest, inclined at 27 degrees to the line of sight.

• October 9th - late evening: The Moon and the Hyades Cluster

  Late evening on the 9th, rising in the East will be the Hyades Cluster along with a waning Moon.

• October 17th - before dawn: Venus and Mars below a thin crescent Moon.

  Looking Eastwards before dawn on the 17th, a thin crescent Moon will be seen high above Venus and Mars.

• October 24th - after sunset: Saturn below a thin waxing crescent Moon

  After sunset on the 24th, Saturn will be seen lying below a thin waxing crescent Moon.

• October 11th: Mons Piton and Cassini

  Best seen just before Third Quarter, Mons Piton is an isolated lunar mountain located in the eastern part of Mare Imbrium, south-east of the crater Plato and west of the crater Cassini. It has a diameter of 25 km and a height of 2.3 km. Its height was determined by the length of the shadow it casts. Cassini is a 57km crater that has been flooded with lava. The crater floor has then been impacted many times and holds within its borders two significant craters, Cassini A, the larger and Cassini B.

  Claire Bretherton from the Carter Observatory in New Zealand speaks about the southern hemisphere night sky during October 2017.

  Kia ora and welcome to the August Jodcast from Space Place at Carter Observatory in Wellington, New Zealand.

  The Planets

  We're really noticing the lighter mornings and evenings now as the Earth continues its orbit around the Sun and we move closer to our southern hemisphere summer. By the end of October the Sun won't set until around 8pm here in Wellington. As we leave Jupiter behind on its outer orbit it is slowly disappearing from our skies, it still sits low in the west at the beginning of the month, setting as twilight ends, but by mid month will be lost in the sunset.

  • Saturn

    Saturn is now our best bet for evening planet viewing, sitting midway up the western sky after dark. A little below and to the left of the planet is Antares or Rehua, marking the heart of Scorpius, which we call te Matau a Maui, the fish hook of Maui here in New Zealand.

  • Zodiacal Light

    October is a good time to look out for the zodiacal light, a triangular glow visible in the west after sunset in a clear, dark sky, tilting up towards Antares. The zodiacal light is caused by sunlight reflecting off dust along the plane of our solar system. This plane is marked by the ecliptic, the apparent path of the Sun across the sky, which runs through the constellations of the zodiac. At this time of year the ecliptic makes a steep angle with the horizon, making the zodiacal light easier to observe.

  • Neptune and Uranus

    Whilst not easily seen with the naked eye, Neptune and Uranus are also in our evenings skies, with Neptune in the constellation of Aquarius and Uranus is in neighbouring Pisces. Uranus reaches opposition on the 20th of the month, when it will be directly opposite the Sun in the sky and overhead at around 1am now that we are observing daylight saving. At magnitude 5.7 it is just on the edge of naked eye visibility, but with binoculars should be easy to spot. A small telescope may reveal it as a disk, with a greenish hue.

  Constellations

  Just to the north of Pisces is the constellation of Pegasus, the winged horse, which appears to leap across the northern horizon in our late evening sky. Pegasus is easy to spot by the ''Great Square'' of stars that makes up his body.The brightest star in the constellation is the reddish star Epsilon Pegasi, marking the horse's muzzle. This star is commonly known as Enif, deriving from the Arabic word for nose. Epsilon Pegasi is an orange supergiant, around 12 times the mass of the Sun, and with a radius some 185 times larger.

  Nearby, to the bottom left of Enif, (and visible in the same binocular field of view) is the globular cluster M15, one of the oldest and best know star clusters in the sky, with an estimated age of around 12 billion years. The cluster is located around 34,000 light years away and measures 175 light years across. M15 is probably the most densely packed globular cluster in our galaxy, with half of its mass concentrated within 10 light years of the centre. It has been suggested that this massive concentration of stars may be caused by a rare type of supermassive Black Hole in the clusters core.M15 also contains the planetary nebula Pease 1, the first to be found within a globular cluster. At magnitude 15.5, this is a faint object, and a telescope with an aperture of at least 300mm would be needed to observe it.

  On the opposite side of the sky, the Southern Cross, or Te Punga sits low in the south south west, its long arm pointing up across the sky to Achernar in the south east. Achernar is at the tip of the constellation of Eridanus, the river, and is also known as Alpha Eridani. It is the brightest star in the constellation, and the 9th brightest in the night sky. It is a hot, blue main sequence star around 7 times the mass and over 3000 times the luminosity of the Sun. The traditional name, Achernar, derives from the Arabic phrase ''Al Ahir al Nahr'' meaning the end of the river, although interestingly this name was once given to Theta Eridani, now known as Acamar, which was the brightest star in the constellation visible from Ancient Greece.Achernar spins on its axis extremely quickly, completing one rotation in just over 2 days. This high rotation speed gives the star a flattened shape, with the diameter of its equator over 50% greater than that of its poles. Infrared observations from the Very Large Telescope in Chile have also identified a smaller companion star, with around twice the mass of the Sun. The two are extremely close, with a separation of just over 12 AU, slightly larger than the distance from the Sun to Saturn, and orbit once every 14-15 years, although the highly distorted shape of the primary makes these numbers hard to determine.

  Below Achernar, just above the south south east horizon, our second brightest night time star, Canopus, twinkles colourfully. The two make an almost equilateral triangle with the southern celestial pole, the point in the sky directly above the south pole of the Earth, about which the whole sky appears to rotate. Another easy way to find this is to but one hand an Achernar and a second hand on Gamma Crucis at the top of the Southern Cross and clap them together in the middle.

  • Magellanic Clouds

    Between the southern celestial pole and Achernar, and above Canopus, you may be able to spot two small fuzzy patches of light, easily seen with the naked eye on a dark, moonless night. These are the Large and Small Magellanic Clouds, two small irregular dwarf galaxies that neighbour our own. Whilst these galaxies are much smaller than the Milky Way, they still contain billions of stars. To the top-right of the SMC you may spot a faint fuzzy 'star'. This object is not actually associated with the SMC but is a beautiful globular cluster called 47 Tucanae, or NGC 104 located just a tenth of the distance away on the outskirts of our own galaxy. At around magnitude 4.1 it is the second brightest globular cluster in the sky, after Omega Centauri, and can be easily seen with the naked eye. With a binoculars or a small telescope it is a wonderful sight, revealing a densely packed central core, whilst a larger telescope will start to resolve some of its millions of ancient stars.

  • Orion

    At the far end of the long winding river of Eridanus is our summer constellation of Orion, the hunter, with bright, blue Rigel the first star to rise after around 11pm mid-month. Below, and following around and hour and a half later is stunning red Betelgeuse, marking the hunter's shoulder or armpit. We'll be exploring this part of the heavens in much more detail over the next few months as it moves into our evening skies, but this month we turn our attention to the constellation in the morning skies, the best time to see the Orionid meteor shower, the radiant of which lies a little below and to the right of Betelgeuse. The Orionids peak on the 21st-22nd of October when the Earth passes through the trail of dust and debris left behind by Comet Halley. The shower can reach rates of 25 meteors per hour, but from the latitude of New Zealand around 10 per hour is more likely with the radiant below the horizon until the early hours of the morning. The best time to look is in the hours before dawn. Try looking around 20 degrees away from the radiant, so the areas from Taurus around through the top of Orion to Canis Major are probably your best bet. Whilst the meteors may be few and far between they also tend to travel quite long distances on the sky and sometimes leave persistent trails of ionized gas behind them that can last for several seconds. With a new moon on the 20th, just before the peak, leaving us with nice dark skies, you should have a good chance of Orionid spotting this year.

  Wishing you clear skies from the team here at Space Place at Carter Observatory.

The Night Sky

Northern Hemisphere

Ian Morison tells us what we can see in the northern hemisphere night sky during September 2017.

The Planets

• Jupiter: Now five months after opposition, Jupiter can still just be seen very low in the southwestern sky after nightfall, lying at an elevation of some 10 degrees 45 minutes after sunset. By month's end it will be at an elevation of just 4 degrees at dusk. With a magnitude of -1.7 and an angular size of ~31 arc seconds it will be at its dimmest and smallest during this year's apparition and is too low for any reasonable telescopic views. At the start of September, Spica, Alpha Virginis, lies some 4 degrees to its lower left. Jupiter, moving eastwards passes 3 degrees to the upper right of Spica on September 11th. Now moving down towards the lower part of the ecliptic, next year it will only have an elevation of 25 degrees when due south whilst for the following two years an elevation of just 18 degrees.
  
  
• Saturn came into opposition back on June 11th and so will be seen in the southwest as darkness falls and sets late evening. It shines initially at magnitude +0.4 falling to +0.5 during the month and has an angular size of ~16.5 arc seconds. With an angle of 26.8 degrees inclination to the line of sight, the rings are virtually as open as they ever can be. Their maximum tilt, at 27 degrees, will come in October - the first time since 2002. It is sad that Saturn, now lying in the southern part of Ophiuchus between Sagittarius and Scorpius, only reached an elevation of ~17 degrees above the horizon when due south, so hindering our view of this most beautiful planet. If imaging Saturn (or Jupiter), Registax 6 has a tool to align the red, green and blue colour images to largely remove atmospheric dispersion from the image. At somewhat over £100 one can purchase the ZWO atmospheric dispersion corrector which uses two, contra rotating, prisms to carry out an even better correction - and which can also be used for visual observing.
  
  
• Mercury. has now become a morning object and will form a very tight grouping with Mars and Regulus, in Leo on the morning of the 5th. They will lie about 15 degrees below Venus. Binoculars will be needed to observe them in the bright twilight but please do not use them after the Sun has risen. Rising in elevation during the first part of the month, by the 10th it will have brightened to zero magnitude and lie just half a degree to lower right of Regulus. Mercury reaches greatest elongation, some 18 degrees from the Sun on the 12th - its best morning apparition this year. On the 14th, it lies 11 degrees to the lower left of Venus whilst, before dawn on the 16th, it closes to just 0.3 degrees from Mars. In the final week of September, moving back towards the Sun, it will be lost in the Sun's glare. .
  
  
• Mars has now become a morning object at the start of its new apparition. Lying in Leo, and still not easily seen in the pre-dawn sky, it forms a tight grouping with Mercury and Regulus on the 5th some 15 degrees to the lower left of Venus. During the month, Mars has a magnitude of 1.8 and an angular size of just 3.6 arc seconds so no details will be seen on its salmon-pink surface. As the month progresses Mars rises higher in the sky before dawn and moves closer to Venus which is now moving back towards the Sun
  
  
• Venus is visible in the east before dawn this month, rising around 2 hours before sunrise. Its magnitude remains at -3.9 during the month as its angular diameter shrinks from 12.4 to 11.2 arc seconds. However, at the same time, its illuminated phase increases from 84 percent to 91 percent - which explains why its magnitude does not change.
  
  
Highlights of the Month

September - Find the globular cluster in Hercules and spot the 'Double-double' in Lyra: There are two very nice objects to spot with binoculars in the south-eastern sky well after dark this month. Two thirds of the way up the right hand side of the 4 stars that make up the 'keystone' in the constellation Hercules is M13, the best globular cluster visible in the northern sky. Just to the left of the bright star Vega in Lyra is the multiple star system Epsilon Lyrae, often called the double-double. With binoculars a binary star is seen but, when observed with a telescope, each of these two stars is revealed to be a double star - hence the name!

September - A good month to observe Neptune with a small telescope. Neptune comes into opposition - when it is nearest the Earth - on the 2nd of September, so will be well placed to spot this month. Its magnitude is +7.9 so Neptune, with a disk just 3.7 arc seconds across, is easily spotted in binoculars lying in the constellation Aquarius as shown on the charts. It rises to an elevation of ~27 degrees when due south. Given a telescope of 8 inches or greater aperture and a dark transparent night it should even be possible to spot its moon Triton.

September 5th - before dawn: Mars Mercury and Regulus. Before dawn on the 5th, Mercury and Mars will be seen in a close grouping with Regulus in Leo. A very low eastern horizon will be needed to spot them with the use of Binoculars - but please do not use them after the Sun has risen. [The magnification given by the binoculars reduces the effective brightness of the pre-dawn light.]

September 12th - before dawn: the Moon closes on the Hyades Cluster. Before dawn on the 12th, the Moon will be seen closing onto the Hyades Cluster in Taurus.

September 16th - before dawn: three planets below the Moon. Before dawn on the 16th, a thin crescent Moon will be seen high above Venus, Mars and Mercury. Regulus lies between Venus and Mercury.

September 26th - after sunset: Saturn below the crescent Moon. After sunset on the 26th, Saturn will be seen lying below the Moon.

September: 12th and 28th: the Alpine Valley. These are good nights to observe an interesting feature on the Moon if you have a small telescope. Close to the limb is the Appenine mountain chain that marks the edge of Mare Imbrium. Towards the upper end you should see the cleft across them called the Alpine valley. It is about 7 miles wide and 79 miles long. As shown in the image a thin rill runs along its length which is quite a challenge to observe. Over the next two nights following the 28th the dark crater Plato and the young crater Copernicus will come into view. This is a very interesting region of the Moon!

Southern Hemisphere

Claire Bretherton tells us what we can see in the southern hemisphere night sky during September 2017.

Kia ora and welcome to the August Jodcast from Space Place at Carter Observatory in Wellington, New Zealand.

The Planets
• Saturn: After what felt like a long, cold, wet winter here in Wellington, September marks the start of spring in the southern hemisphere. As we head towards the equinox on the 23rd of the month we see a rapid change in our daylight hours, with our days getting longer and our nights shorter. Equinox means "equal night" because we have the same number of hours of daylight and the same number of hours of darkness at this time of year. By the end of September the Sun won't be setting until nearly half past 7.The mission has revealed the complexity of Saturn's ring system, identified numerous new moons, and provided some of the most stunning images of the solar system that we have ever seen. It has found liquid oceans and a thick atmosphere on Titan, with conditions that may be similar to early Earth, and exploration of the icy moon Enceladus has revealed a hot spot at the southern pole, icy jets spewing out from the surface and a vast ocean below the ice.
  
  
• Neptune: Whilst there are only two evening planets you can see with your own eyes, Neptune is also in our evening skies, with Uranus joining it before 10pm. Both can be picked out with binoculars, and you may even notice a greenish colour to Uranus, but Neptune will be indistinguishable from a faint star.Now is the best time to look for the eighth planet though, as it reaches opposition on the fifth of the month, when it will be directly opposite the Sun in the sky and at its highest in the north at midnight. At around this time the planet will also be at its closest and brightest, shining at magnitude 7.8, and is sat less than a degree just below and to the right of the 3.8 magnitude star lambda aquarii, but you'll still probably need a detailed finder chart to spot it. Unfortunately, the full moon passes close to Neptune just after opposition, so it may be easier to find a week or two later.
  
  
Stars

The bright stars Vega and Canopus mark north-south around dusk this month, guiding our eye to the bright band of the Milky Way passing high overhead. Along with the nearby bright stars of Deneb, in Cygnus the swan, and Altair, in Aquila the eagle, Vega forms part of the "winter triangle" as seen here in the southern hemisphere.

To the south-east of Capricornus is the faint constellation of Piscis Austrinus, the southern fish, with its only bright star, Fomalhaut, marking the mouth of the fish. Fomalhaut is the 18th brightest star in the night sky, and the only, lonely bright star in its vicinity.Follow up observations, however, failed to confirm the planet and left many doubting its existence. It took until 2012 before Fomalhaut b was independently detected and confirmed. Its controversial past has earned it the nickname "the zombie planet", a planet resurrected from the dead.

Wishing you clear skies from the team here at Space Place at Carter Observatory.

Northern Hemisphere

Ian Morison tells us what we can see in the northern hemisphere night sky during August 2017.

The Planets

• Jupiter Now four months after opposition, Jupiter can still be seen low in the southwestern sky after nightfall. It sets at about 1 am BST as July begin. As the month progresses its brightness falls from -1.9 to -1.7 magnitudes as its angular size falls from 34 to 32 arc seconds. It lies in Virgo, initially some 8 degrees to the west of Spica, reducing to 4 degrees as the month progresses and will pass Spica on September 11th on its journey towards the lower parts of the ecliptic. Next year it will only reach an elevation of some 25 degrees when due south and, in the following two years, just 18 degrees before it moves back towards the more northerly parts of the ecliptic. Even so, with a small telescope one should easily be able to see the equatorial bands in the atmosphere, sometimes the Great Red Spot and up to four of the Gallilean moons as they weave their way around it.
  
  
• Saturn came into opposition on June 11th and so will be at its highest elevation due south as darkness falls. It shines initially at magnitude +0.3 falling to +0.4 during the month and has an angular size of ~17 arc seconds. With an angle of 26.8 degrees inclination to the line of sight, the rings are virtually as open as they ever can be. Their maximum tilt, at 27 degrees, will come in October - the first time since 2002. Saturn ceases its westwards, retrograde, motion on August 25th. It is sad that Saturn, now lying in the southern part of Ophiuchus between Sagittarius and Scorpius, only reaches an elevation of ~17 degrees above the horizon when due south so hindering our view of this most beautiful planet. If imaging Saturn (or Jupiter), Registax 6 has a tool to align the red, green and blue colour images to largely remove atmospheric dispersion from the image. At somewhat over £100 one can purchase the ZWO atmospheric dispersion corrector which uses two, contra rotating, prisms to carry out an even better correction - and which can also be used for visual observing.
  
  
• Mercury Given a very low western horizon, Mercury, showing an 8 arc second disk and shining at magnitude +0.4 might just be seen after sunset at the beginning of August. Binoculars may well be needed but please do not use them until after the Sun has set. It passes between the Earth and the Sun (inferior conjunction) on August 26th.
  
  
• Mars passed behind the Sun in July, but will be hidden in the Sun's glare all month so cannot be observed.
  
  
• Venus is visible in the east before dawn this month, rising around 3 hours before sunrise. Its magnitude dims slightly during the month from -4 to -3.9 as its angular diameter shrinks from 14.5 to 12.5 arc seconds. However, at the same time, its illuminated phase increases from 74 to 83% which explains why the magnitude does not drop too much. Its elevation before sunrise is greatest on August 2nd when Venus lies close to the open cluster M35 in Gemini.
  
  
Highlights of the Month

August - Find the globular cluster in Hercules and spot the 'Double-double' in Lyra. Just to the left of the bright star Vega in Lyra is the multiple star system Epsilon Lyrae, often called the double-double. With binoculars a binary star is seen but, when observed with a telescope, each of these two stars is revealed to be a double star - hence the name!

August - A good month to observe Neptune with a small telescope. Neptune comes into opposition - when it is nearest the Earth - on the 2nd of September, so will be well placed both this month and next. Its magnitude is +7.9 so Neptune, with a disk just 3.7 arc seconds across, is easily spotted in binoculars lying in the constellation Aquarius as shown on the chart. It rises to an elevation of ~27 degrees when due south. Given a telescope of 8 inches or greater aperture and a dark transparent night it should even be possible to spot its moon Triton. (This is my objective around the end of the month!)

The Moon and Saturn - Late evening on the 2nd of August, the waxing Moon will be seen to the upper right of Saturn. Antares lies down to its lower right.

The mornings of August 12th and 13th: midnight to dawn - look out for the Perseid meteor shower. If clear, these mornings should give us a chance of observing the Perseid meteor shower - produced by debris from the comet Swift-Tuttle. The early morning of the 12th August will give us the best chance, if clear, of viewing the shower, but the peak is quite broad and so it is well worth observing on the nights before and after. Most meteors are seen looking about 50 degrees from the 'radiant' which lies between Perseus and Cassiopeia. This year a gibbous Moon rises before midnight so will be low in the sky for some time the early hours of the 12th so it will be best to observe them as soon as it is really dark. Moonlight will hinder our view, but it should still be possible to spot many meteors. NB: As we need to view a very wide area of sky, normal binoculars would be of no use, but the Vixen SG 2.1 x 42 that I have just reviewed in the Astronomy Digest, could be useful as they will darken skylight from the Moon somewhat and enable fainter meteors to be seen - albeit over a smaller field of view.

16th August 07:40 - 08:40 BST: A daylight Occultation of Aldebaran - In the early morning of the 16th, Aldebaran will be occulted by the Moon - visible with a telescope (but keep it well away from the Sun). The times are for London and will vary somewhat across the country. In a line from Leverburgh on the Isle of Harris across to Wick, a grazing occultation will be seen at 8:01 BST.

19th August - before dawn: Venus and a thin crescent Moon - Before dawn on the 19th, if clear, Venus will be seen just 2 degrees above a very thin waning crescent Moon.

25th August - after sunset: Jupiter below a thin crescent Moon - After sunset on the 25th, if clear, Venus will be seen below a thin waxing crescent Moon.

August 14th and 30th: The Straight Wall - The Straight Wall, or Rupes Recta, is best observed either 1 or 2 days after First Quarter (30th August: evening best) or a day or so before Third Quarter (evening of the 14th August best). To honest, it is not really a wall but a gentle scarp - as Sir Patrick has said "neither is it a wall nor is it straight"!

Claire Bretherton tells us what we can see in the southern hemisphere night sky during August 2017.



Kia ora and welcome to the August Jodcast from Space Place at Carter Observatory in Wellington, New Zealand.

The Planets
• Mercury finishes its best evening appearance of the year this month. At the beginning of August it sits low in the west after dark, just above Regulus, the brightest star in Leo, setting around 7:45. By mid month it will disappear from view, lost in the evening twilight as it heads back towards the Sun in our skies. Jupiter is a little further north, midway up our northwestern skies. It is slowly moving below and towards the right of Spica over the course of the month. Both are quickly dropping down our evening skies, with Jupiter setting at around 11pm at the beginning of August, but by around 9:30 at the end.
  
  
• Saturn - Further around still, Saturn is high in the northeast after dark, with Antares above and to the left, and remains in our sky for most of the night. A waxing gibbous moon passes close to Saturn on the 3rd and 31st of the month, whilst on the evening of the 25th, a thin 3 day old crescent Moon will sit just below Jupiter.
  
  
• The Moon - On the 22nd of August the Moon will pass directly between the Earth and the Sun, causing a total Solar eclipse. The eclipse path will run across the United States, but unfortunately no part of it will be visible from New Zealand. The next total Solar eclipse visible from our shores won't be until July 2028.
  
  
Constellations

Last month we looked at some of the amazing objects in Scorpius and Sagittarius, towards the centre of the Milky Way. This month we'll move along a little from our Galaxy's bright centre to where it passes overhead through Centaurus, Crux, the Southern Cross, and the constellations of Carina, Vela and Puppis that make up the great ship Argo Navis.

Crux - Crux, the Southern Cross lies on its side after sunset in the south western sky, with the Diamond Cross and false cross below. Above Crux are Alpha and Beta Centauri, the brightest stars in the constellation of Centaurus. Known as the pointers, they guide our eye to Gamma Crucis, the star at the top of Crux, and help us identify the true Southern Cross.

Omega Centauri - To the right of the pointers, and just outside the main band of the Milky Way is the spectacular globular cluster Omega Centauri. This is by far the largest and brightest globular cluster in the Milky Way appearing as a fuzzy star to the naked eye. With binoculars it is an even more stunning sight, spanning almost a full degree of the sky, twice that of the full moon, whilst a small telescope will show a shimmering ball of stars, with many individual stars visible towards the outskirts.

The Jewel Box - Close to Beta Crucis, in the Southern Cross, is a different type of star cluster. NGC 4755, also known the "Jewel Box", is an open cluster about 6,500 light years away. It is rich and bright with the stars showing an array of different colours, highlighted by an orange-red supergiant. At magnitude 4.2, the Jewel Box can easily be seen with the naked eye. It is dominated by an A-shaped asterism of bright stars, which is observable with binoculars, whilst even a small telescope will reveal a stunning sight. The name comes from Sir John Herschel's vivid description of the cluster as a "casket of variously coloured precious stones".

The colours of these stars tell us how hot they are. The red stars are the coolest, with temperatures around 3000K, yellow stars like our Sun are closer to 6000K, whilst the hottest, bluest stars reach temperatures of 30,000 Kelvin or more. In order to get this hot these stars have to use a huge amount of fuel very quickly, so they don't live very long - they live fast and die young. The most massive live for just a few million years. The fact that NGC4755 still contains a number of these hot blue stars tells us that it is relatively young, in fact it is one of the youngest star clusters known, with an estimated age of just 14 million years.

Coal Sack - Just to the left is a dark patch known as the Coal Sack nebula. This is a huge cloud of interstellar dust and gas some 700 light years away. It is so thick and dense that it obscures the light from more distant stars, appearing as a darkened area against the bright backdrop of the Milky Way. Aboriginal astronomers have observed the Coalsack for at least 40,000 years, whilst to Māori here in New Zealand it is known as te Patiki or the flounder.

Carinae Cluster - Below the Coalsack, at the tip of the Diamond Cross asterism in Carina is the Theta Carinae cluster, or IC 2602, an open cluster containing around 60 individual stars. At magnitude 1.9 it is the third brightest open cluster in the sky and is often known as the Southern Pleiades, although it is still much fainter than its northern counterpart. The cluster spans around 50 arcminutes, over 1.5 full moon diameters, so it is best viewed with binoculars or a low powered telescope giving a wide field of view.

Carinae Nebula - Around 4 degrees to the right of Theta Carinae is the famous NGC 3372, the Eta Carina nebula, a huge cloud of glowing gas estimated to be around 7500 ly away. At 4 times the size of the Orion Nebula, it is one of the largest nebulae of its type in our skies. With the naked eye you'll be able to pick out the brightest central areas, but with binoculars you should be able to see Eta Carinae itself as a golden star within the nebula. Eta Carinae is actually a system of at least two stars, which combined are around 5 million times more luminous than our Sun. The largest has around 90 times the Sun's mass and is so bright that the radiation pressure it produces is almost too strong for the gravity holding it together, causing a constant stream of material out into space.

Highlights of the Month

Venus - In the morning skies, Venus is now rising around 5am. The Moon will pass nearby on the 19th, sitting just above Venus in the north east at sunrise. The two will move towards the north by midmorning, providing a perfect opportunity to try and spot Venus in the daylight, with Venus sat just to the right of a thin waning crescent Moon.

Wishing you clear skies from the team here at Space Place at Carter Observatory.