Weekend Sky Report

Messier 3 is a remarkable globular cluster. It’s over 33,000 light years away, but it’s bright enough to see with a small telescope, which means it’s dense. Around half a million stars exist there. It’s considered by some to be the most beautiful of its kind. But what is a globular cluster?

Globular comes from the Latin globulus, meaning “small sphere.” Small they are not… this one is an estimated 90 light years across. But compared to open clusters, they do seem smaller. Globulars are like open clusters in that they’re a group of nearby stars bound together by gravity, but they form above the galactic plane, or at the outer edge of the galaxy where their collective gravity can hold it together tightly away from the influence of passing bodies, whereas open clusters form further in where the gravity from other stars can disrupt its shape. For this reason, it takes a long time for globular clusters to form.

To find Messier 3, first find bright orange Arcturus. It’ll be in the eastern sky before midnight. One way to find Arcturus is to follow the curve of the handle of the big dipper… arc to Arcturus. Once you’ve found Arcturus, look for a dimmer white star called Cor Caroli (kor CARE-uh-lie). If you’re observing in the evening, it’s above and to the left of Arcturus, next to the handle of the big dipper. Trace a line between Arcturus and Cor Caroli. Point your telescope to the middle of that line and scan slightly downward toward Arcturus until you see what looks like a dim, fuzzy star. That’s Messier 3.

When you find it, you’ll be looking at a globular cluster that’s an estimated 8 billion years old. More than half the age of the universe itself.

Mizar (MY-czar) is the middle star in the handle of the big dipper, and with nothing more than decent eyesight... that is, no telescope, no binoculars, you can spot its companion, Alcor (al-KOR). In fact, Mizar and Alcor have been used as an eyesight test for hundreds, maybe even thousands of years. 13th century Persian astronomer Zakariya al-Qazwini wrote about it. A Japanese myth calls the fainter Alcor “The lifespan star,” and at one time was believed that if you couldn't see both stars, it was a sign of old age and that you would die within the year.

Of course we know that's not true... but what we also know is that Mizar itself isn't just one star... if you look at Mizar through a telescope, you'll notice that it's a binary. Mizar A and Mizar B. That was discovered in the 1500s... but through spectroscopic observation, we know that both Mizar A and Mizar B are BOTH binaries, making it a four-star system. But we're not done yet...

It was long believed that Alcor, while appearing very close to Mizar in the night sky, was actually not at all related. That it was probably just a bright star behind Mizar. But in 2009, it was discovered that not only are the two stars gravitationally bound, but that Alcor itself is a binary system as well. So what looks to the naked eye like two stars very close together is actually a six-star system.

So this weekend, test your eyesight with the middle star—or... stars... in the handle of the big dipper. Then, if you have a telescope, get closer and split Mizar A and Mizar B.

This week, scientists working with an array of radio telescopes that amounts to an aperture roughly the size of the Earth itself, released an image of the supermassive black hole at the center of M87, a supergiant elliptical galaxy that’s in the evening sky tonight.

M87, also known as Virgo A was discovered in 1781 by French astronomer Charles Messier, who’s known for his list of deep sky objects. M87 is part of the Virgo cluster of galaxies which, as the name suggests, are in or around the constellation Virgo, which rises from the east in the early evening and sweeps across the southern sky all night.

Now depending on when you observe, the location will change of course. But at 9:30, look to the east and find bright orange Arcturus. To the right, and a little lower on the horizon is Spica. Now look above those two stars and complete a big equilateral triangle with the star Denebola. From there, scan slowly down toward, but not quite to the center of that triangle. When you see one, or a series of very dim, fuzzy objects, you’ve found it. But which one is M87? Near M87 is also M84 and M86. Of those three, M87 is the brightest one, but not by much. The other two are practically right next to each other, with M87 below and to the left.

Now, if you don’t find it, don’t feel bad. These are VERY difficult to see, even with larger telescopes. But if you do see it, you’ll be looking at light that’s taken 53 million years to get here, and an enormous galaxy whose heart we can now see.

Spring doesn't exactly provide the most reliable stargazing weather. Rain and moisture from low pressure and fluctuating temperatures can really put a damper on things. But if we get a clear night, sweeping east to west in the night sky this time of year, is the Coma Star Cluster.

The Coma Star Cluster is an open cluster of about 40 stars--the brightest of which form a "V" shape you can see with the naked eye under dark skies.

The name comes from the constellation it's found within. Coma Berenices (bear-uh-NYE-sees) is a small constellation that includes the star cluster, and it's named after Queen Berenice II of Egypt. It's the only modern constellation named after an historic figure--not a mythological one.

Now, as far as star clusters go, this one's not that big. 40 stars is nothing compared to some other popular targets. But it IS close... around 280 light years away. Other bright stars we can see tonight like Betelgeuse, Rigel, and Antares are at least twice as far away.

And yes, you need DARK skies. In the suburbs, you'll probably need binoculars or a telescope with a wide field of view in order to see the cluster. Far enough outside of town, you'll just need your eyes... and of course clear skies.

To find the Coma Star Cluster, look to the east around 9:30 and find the bright orange Arcturus. From there, look higher and slightly to the right. Once you see the bluish white "V," you've found it. Binoculars or a telescope will of course allow you to see the dimmer stars of the cluster, making it all the more brilliant.

Sirius, glides low across the southern evening sky this time of year. It’s called the Dog Star because it’s at the heart of Canis Major, Latin for the Greater Dog. One of two dogs that follow Orion the Hunter.

Within the constellation sits a large star cluster—Messier 41. The only Messier object in Canis Major. From our perspective, it’s about as big as the full moon in the night sky. But under urban and suburban skies, it’s not only outshined by city lights, but by bright Sirius itself. However, to see it, you only need binoculars or a small telescope.

Here’s how to find it… first, find Sirius. It’s the brightest star in the night sky, but there are other bright ones too, so how do you make sure you have the right one? Well, Sirius is the bottom point of the Winter Triangle. A large, nearly perfect equilateral triangle in the southern sky that also includes Procyon in Canis Minor, and Orion’s right shoulder, the bright orange Betelgeuse. Now that you’ve identified Sirius, look at it through binoculars. Most binoculars should have a wide enough field of view to show both Sirius AND Messier 41, which is found below and just to the left of Sirius. If you only have a telescope, another way to find Messier 41 is to draw a line between Sirius and second-brightest star in Canis Major, Adhara, and follow just below that line starting from Sirius, and stop when you see a large, open star cluster. That’s Messier 41.

When you find it, you’ll be looking at a cluster 25 light years across, and 2300 light years from Earth, containing around 100 stars.

It’s a great time of year for open clusters. There’s a lot to choose from in the evening sky. The Pleiades, the Hyades, Coma, Alpha Persei… but one of the more overlooked star clusters, especially under bright urban skies, is Messier 44, or the Beehive Cluster. Now, it’s dimmer and harder to find than those other clusters, so suburban observers will need to get creative. Here’s how I find it.

The Beehive Cluster is right smack in the middle of Cancer the Crab, which is actually a very dim constellation. To find it, make a big triangle between Regulus, the bright blueish heart of Leo, Procyon, the dimmer star of the winter triangle, and either of the two heads of Gemini—Castor or Pollux. Now if you don’t know where these stars are at all, you might have some trouble. Here’s where to look. Early in the evening, between 7:00 and 8:00, they’ll be to the east with Regulus being almost due east. Procyon will be to the southeast, and the heads of Gemini are high above those two. This large acute triangle with Regulus at the sharpest point will sweep across the southern sky. It’ll be highest in the sky and due south just before 11pm. Once you form that triangle of Regulus, Procyon, and either head of Gemini, Cancer the Crab is right in the center. So scan with your telescope until you see a loose cluster of dozens of stars. That’s M44, the Beehive Cluster.

When you find it, you’ll be looking at one of the first objects ever studied with a telescope… by Galileo himself.

All right—I’m no trickster, so I’d make a lousy leprechaun. No… there are no green stars. But there are a few that can appear green.

Blue stars that are really close to red stars can appear to us as a greenish blue. One good example is Antares B, the binary companion to the red giant Antares A, the heart of Scorpius.

If you wake up EARLY on St. Patrick’s Day, or any day in the next month or so, you can’t miss bright orange Antares A low in the southern sky. To see Antares B, you’ll need a decent-sized telescope at least 6 inches in diameter. Point it right at Antares, and look for a much dimmer, greenish blue companion. That’s Antares B. Now again, the only reason it appears green is because a giant bright red star is right next door. It’s an optical trick. But as long as you’re outside with a big telescope, there are a couple other nearby objects you’ll want to see.

First, let’s address the VERY bright object to the left of Antares. That’s Jupiter. Of course, any telescope should show you its four largest moons. Larger telescopes will show you the cloud belts.

And now for the pot of gold…

With Antares in your eyepiece, move to slowly to the right, or West until you see what looks like a dim, fuzzy ball of light. That’s Messier 4, an ancient globular cluster over 12 billion years old, and over 7000 light years away.

So if you’re up for some early morning observation, there’s plenty to see in the southern sky.

A lot of attention gets paid to Orion’s right shoulder… the red giant Betelgeuse. It’s massive, it’s enormous, it may go supernova in our lifetime… but the hunter’s left shoulder is pretty interesting too.

Bellatrix, latin for Female Warrior, is also known as the Amazon Star, after the greek legend of a mythical female warrior tribe. It’s almost 4 times hotter than our sun, more than 5.5 times its size, more than 8.5 times as massive, and more than 6,000 times brighter.

And it’s young… a newborn compared to our star… only about 25 million years old. But it is a different kind of star after all... Bright, hot, massive blueish stars like Bellatrix are classified as B-type stars, which are so energetic that they don’t live very long. The hotter the fire, the faster the fuel burns… same principle.

One of the more interesting things about Bellatrix is the fact that most of the stars in Orion have been shown to originate from around the same place. But Bellatrix is so much closer to our solar system than almost any of the stars in Orion that it’s definitely independent of its neighbors in our night sky at only around 250 light years away. Compare that to the stars in Orion’s belt at 1200 to 2000 light years from Earth.

And for a long time, Bellatrix was considered by scientists to be one of the most stable stars in the night sky in terms of brightness, so it was used as a control to measure the variable brightness of other stars. But now, with more modern technology and methods, we know that Bellatrix misbehaves a little too. As the saying goes: Well-behaved women seldom make history.

Welcome March with a classic Spring constellation with a hidden secret.

Welcome March with a classic Spring constellation with a hidden secret.