Weekend Sky Report

Orion is known among amateur astronomers as a constellation that hosts a trove of deep sky objects. But the rest of us just know it as... the one with the belt. The great thing about Orion though, is that you don’t really have to know what you’re doing to find lots of great targets. You can pretty much just scan the constellation with any size telescope and see a slew of open star clusters. One of the most famous deep sky objects, the Orion Nebula, is located below Orion’s Belt, where his sword might be. Look for it sometime.

But let’s talk about the belt. Lots of people can see just those three stars and know what they’re looking at. But look a little closer at the belt with a telescope, or even a good pair of binoculars, and you’ll see many more stars. An open cluster known as Collinder 70 is centered around the middle star, Alnilam (AL-nih-lum). Point your telescope right at it and you’ll notice a smattering of bluish stars surrounding it.

And bright Alnilam itself is a pretty interesting star. The brightest and most well-known stars in Orion are the red supergiant Betelgeuse, Orion’s right shoulder, and the blue supergiant Rigel, the hunter’s left foot. But Alnilam is also a blue supergiant. And some estimates put it at over 60 times the mass of the sun, which is far more massive than any of the other bright stars in Orion.

Sure, there's stars out at night, but right now, there's a moon out in the morning...

I'm Matt Pelsor... and this is your Weekend Sky Report.

There was a full moon this past Tuesday, which means this weekend the moon is in the waning gibbous phase. Waning moons are out in the morning, and this week's mostly clear skies have given us a good view--particularly those of us who drive west into work. If we get clear skies this weekend, take a moment to look west at the gibbous moon. If you have a telescope, see how much you can make out in the daylight. You'll probably be surprised at just how much you can see, even with the sun washing out most of the dimmer details.

Another thing to look forward to will be a lesser-known meteor shower that's expected this coming Thursday night. Astronomers who crunch the probability numbers for meteor showers predict that this year's Alpha Monocerotid meteor shower could produce a burst of around 100 meteors in just 15 minutes, but that burst could also last up to 40 minutes--we just don't know for certain. This was predicted by looking at a similar burst in 1995 when circumstances were nearly identical.

To see it, look to the east no later than 11:15 this coming Thursday night. Find the three bright stars that make up the winter triangle--Sirius, the brightest star in the sky; Betelgeuse, Orion's right shoulder; and the dimmer of the three, though still very bright, Procyon at the bottom. The radiant for this meteor shower is predicted to be right around Procyon. Bundle up though, because it could take until just before midnight for the peak.

If you see it, you'll be watching the ancient remnants of a comet we haven't yet identified, hitting the Earth's atmosphere at over 140,000 miles per hour.

I'm Matt Pelsor--happy skywatching.

Observations of the bright, open cluster known as The Pleiades have been recorded since the 17th century BC, and likely even before that. It was scientifically and spiritually significant to many ancient cultures across the globe, and continues to educate and inspire observers today.

The Pleiades is a collection of B-type stars, which are bright, hot, and blue in color. And the stars of the Pleiades are close too—around 450 light years away, which contributes to its brightness. And while you don’t need a telescope or even binoculars to appreciate the Pleiades, it certainly helps.

The Pleiades is also known as the Seven Sisters, after the seven daughters of Atlas and Pleione in Greek Mythology. Observers with good eyesight under dark skies will count seven stars in the cluster. It wasn’t until Galileo looked at the Pleiades through his telescope that dozens of other stars were discovered. Since then, further scientific observations and subsequent calculations have estimated over a thousand stars in the cluster.

To see the Pleiades for yourself, look to the eastern sky in the evening—the later it is, the higher it will be. To the naked eye under suburban skies, it could be confused as a small cloud. Under darker skies, it’ll look more like a star cluster. Once you find it, grab your binoculars or a telescope. Once you look at the Pleiades with a little help, you’ll quickly realize why this star cluster has captured the human imagination for thousands of years.

We all know about... the dippers. Ursa Major and Ursa Minor--the big and little dippers. We know about them because they’re out every night. But there’s another bright northern-hemisphere constellation you should know about… Swirling around the northern sky year-round are the five bright stars that make up... Cassiopeia.

Cassiopeia is popular with amateur astronomers because it’s large, bright, and the main reference point for several deep-sky objects. Things like Double Cluster, the Andromeda Galaxy, Messiers 52 and 103, both open star clusters, and the Owl Cluster, also known as the E.T. Cluster. Yes, THAT E.T. It’s called that because apparently it looks like the movie character. I don’t really see it, but I do enjoy finding it when I can.

Anyway, this weekend, you can find Cassiopeia high to the northeast after sundown. If you were to draw lines between its five bright stars, it would look kind of like a wonky lowercase “W” on its side.

Interestingly enough, if we were to take a quick trip to nearby star system Alpha Centauri, our own sun would appear in Cassiopeia. It would turn the “W” into a bit of a squiggle, and would be appear to be by far the brightest star in the constellation.

Cassiopeia has inspired novels, movies, TV shows, even songs. If we get a clear night this weekend, maybe look up for a little inspiration of your own.

This coming Tuesday, Uranus will be at opposition… meaning the Earth is directly between it and the sun. When a planet is at opposition, it’s at its brightest for the year. Now, even at its brightest, Uranus is still fairly dim. So dim, it wasn’t discovered until the late 18th century when astronomer William Herschel saw what he first thought was a comet, but further observation proved it was indeed a planet beyond Saturn.

This weekend, you can find Uranus in the Eastern sky between the constellations Aries and Pisces with Aries to the left, and Pisces to the right. To find Uranus, trace a line between the second-brightest star in Aries, Beta Arietis (uh-RYE-uh-tiss), and the bottom or cord star in Pisces, Alpha Piscium. From the center of that imaginary line, scan to the right with your telescope. When you see a blue disc, you’ve found it.

And you will need a telescope. Binoculars won’t really work unless they’re particularly powerful or made especially for astronomy. The good news is, almost any telescope should show you at least something if you’re looking in the right spot.

Uranus is a very different planet in a lot of ways. You may remember it being categorized as a gas giant. But since the 1990s when it was discovered that the composition of Uranus and Neptune was in fact VERY different from that of Jupiter and Saturn, the terminology changed. Rather than the hydrogen and helium found in gas giants, ice giants are composed primarily of methane, ammonia, and yes… good old H2O.

Vonnegut’s 1959 novel, The Sirens of Titan, opens with a quote from his character Ransom K. Fern who says “Every passing hour brings the Solar System forty-three thousand miles closer to Globular Cluster M13 in Hercules—and still there are some misfits who insist there is no such thing as progress.”

A great opening… for a great book. Read it sometime. But let’s talk about Messier 13.

The Great Globular Cluster in Hercules, or M13 was discovered by astronomer Edmund Halley in 1714, and found its way into Charles Messier’s catalog of comet-like objects fifty years later. Under the right conditions… a moonless night, and very dark, clear skies, you can see the cluster with the naked eye. Most of us though will need a telescope.

To find the cluster, look high to the west after dark. The later it is, the lower and farther north it will be. There you’ll find the constellation Hercules, which can be identified by the oddly-shaped quadrilateral below the very bright star Vega.  Once you find the four stars that make up Hercules’ torso, find the one furthest to the right. Then, with your telescope, scan slowly toward the star at the bottom of the quadrilateral until you see what looks like a dim, fuzzy star. That’s M13, the Great Globular Cluster in Hercules.

When you find it, you’ll be looking over 25,000 years into the past at a cluster of 300,000 stars.

Sunday is the official full moon, but it’ll pretty much look full all weekend. It rises just after sundown, so it’ll be low on the southeastern horizon in the evening after dark. Often, this can make the moon look bigger, but it’s actually the same size in the sky as if it were straight overhead. A moon low on the horizon can also have a color like yellow, orange, or red. The reason for that is the same reason the sun seems to change color at sunset or sunrise… it’s seen shining through many more layers of atmosphere than if it were higher in the sky. So depending on the conditions, the moon can take on a certain hue.

All that aside, looking at a full moon through a telescope, you notice a lot. The craters, the so-called “seas,” the “Ocean of Storms—“ that’s the big sea… So just what are all those geographic features?

Well, the craters are pretty self-explanatory. They’re impact craters from the eons of the moon’s existence. Some of them are bigger than others, and some have some unique features. Take the Tycho crater. It’s the big one in the southern hemisphere with what looks like lines spiking off of it. That’s impact ejecta. Whatever made the Tycho crater was big enough to spray rock and dust so far across the moon’s surface that we can easily see it from Earth. And we know from samples taken on the Apollo 16 mission that Tycho is a relatively young moon crater, having formed an estimated 108 million years ago. Compare that to the much older “Seas,” which are left over from a time when the moon was geologically active. They’re vast plains of volcanic basalt—basically lava flows.

So take a moment to appreciate the full moon this weekend. Howling is optional.

The first quarter is one of the best phases of the Moon to observe. Because the shadow, or Lunar Terminator; crosses straight down the middle, which gives you a long  swath of detail. Even a small pair of binoculars will spot some of it. But it’s best observed with a telescope. Any telescope will do. Even that toy one in the attic. Get it down because people around the world will be doing the same thing.

International Observe the Moon Night was started in 2010 by NASA. Specifically, the group responsible for its Lunar Reconnaissance Orbiter. Launched in the summer of 2009, it continues to deliver important data today, as well as photos and video of the lunar surface--including the landing sites of all six successful crewed lunar surface missions.

And while you can’t see those with a telescope, you can definitely see detail like craters and mountains. And since the shadow crosses faster during a first quarter moon, you might just notice first light hit a particularly high peak or the craggy rim of a crater if you stay with it long enough.

International Observe The Moon Night also coincides with an opportunity to move your telescope slightly to the right to see the jewel of the Solar System. Saturn is right next door and shows itself as a bright yellow point of light that doesn’t twinkle. Most telescopes will show Saturn’s rings either as two bulges on either side in very small telescopes, or a breathtaking view with stunning detail like the Cassini Division--the split between the two most visible rings.

Tonight’s target has been known since LONG before the telescope was invented. This of course means it can be seen WITHOUT a telescope, but ONLY under very dark skies. And it wasn’t until the early 1800s that, THANKS to the telescope, it was identified as two separate clusters instead of one.

The aptly named Double Cluster is a favorite among budding amateur astronomers. Not only because its brightness makes it easy to find, but also because its beauty keeps observers coming back.

And here in the Northern Hemisphere, Double Cluster never dips below the horizon… so depending on your view, it’s out all night!

To find Double Cluster, look for Cassiopeia. You’ll find it in the northeastern sky in the evening. The later you’re out, the higher it will be... Cassiopeia looks like an elongated, oddly-proportioned “W.” Once you find it, look for the two stars closest together in the constellation. If the “W” were on its side, as it will be tonight, it’s the second and third stars from the bottom. Trace a line between those two stars, then scan down with binoculars or a telescope… following that same line. When you see a double cluster of stars, guess what… you’ve found it. Two brilliant clusters of mostly bluish white stars—but there are a few bright yellow and orange stars for variety.

When you find it, you’ll be looking at one of the younger star clusters you can easily find in the night sky… at only about 13 million years old. To give you an idea, Kangaroos evolved on Earth about two million years BEFORE these stars formed.

The Alpha Persei (PER-see-EYE) Cluster is an open cluster of hot, bluish-white B-type stars. These kinds of stars are so energetic, they don’t live long. So most of the B-type stars we can see in the night sky are, on the cosmic scale, practically newborns.

In fact, by the time most of the stars of the Alpha Persei Cluster first formed, including the bright Mirfak, the dinosaurs were already extinct. Mirfak itself is less than 50-million years old, but it’s already entered old age. It’s a supergiant, having ballooned up to about 60 times the size of our sun. And it’s bright too—five THOUSAND times brighter than the sun.

To find Mirfak, and therefore the Alpha Persei Cluster, look to the northeast. You can find Perseus beneath Cassiopeia in the northeastern sky. The later it is, the higher it will be, but if you miss it this weekend, don’t worry. It will be to the northeast in the evening through early winter.

Under dark skies, you can see the cluster with the naked eye, but if you’re near the city, or if the moon is out, you’ll need some help. A small telescope or even a pair of binoculars should provide enough magnification to notice a loose cluster of bright blue stars around Mirfak. That’s the Alpha Persei star cluster.

The prominence of the constellation Perseus in the evening sky is a sure sign of autumn. It means you’ll be able to observe WITHOUT the help of bug spray… very soon.