Weekend Sky Report

Cooler temperatures means fewer mosquitos, so, at least for me, that means more telescope time.

I’m Matt Pelsor, and this is your weekend sky report.

This weekend, grab a coat or just throw on a hoodie and spend some time finding one of the brighter, and therefore most popular globular clusters.

Messier 22 was the first known globular cluster, which is a term used to describe a dense cluster of thousands, even tens of thousands of stars all bound together by gravity. Perhaps the most interesting thing about globular clusters is their age. They’re believed to contain some of the oldest stars in the galaxy. How they form is still being studied, but one hypothesis is that, as time passes, nearby stars of a certain mass become entangled in each other’s gravity. As the collective gravity of the cluster increases, it attracts more and more passing stars. As millions and even billions of years go by, the cluster grows.

Messier 22 was discovered in 1665 by German amateur astronomer Abraham Ihle (EE-luh) while he was observing Saturn as it passed through the constellation Sagittarius. And coincidentally, that’s exactly where you’ll find it tonight.

To find Messier 22, look to the south, southwest for Saturn. It’ll look like a bright yellow star that doesn’t twinkle. Once you find it, take a look with your telescope. Saturn’s always worth gawking over. Then, with your widest-angle lens, scan slowly to the left, more toward the southern sky. Once you see a dim, fuzzy patch of light, you’ve found it.

If you see Messier 22 this weekend, you’ll be looking at a globular cluster of about 70,000 stars 50 light years across.

I’m Matt Pelsor… happy skywatching.

This weekend, find the popular "Double Cluster" below Cassiopeia to the northeast. Listen to find out how...

This weekend, check out a hot, young… star cluster.

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

The brightest star in the constellation Perseus is Mirfak, and it’s where you need to look to find this weekend’s target.

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.

I’m Matt Pelsor… happy skywatching.

Go out early this evening, September 21, 2018… for a look at a crescent Venus.

If you have a good view of the southwestern sky, head out right around sundown. Even in the twilight, you’ll easily be able to see Venus. But you DO need to be out early enough… it sets around 8:30pm EST.

Because Venus is between the Earth and the Sun, we sometimes see it in phases. And right now, it appears as a crescent in the early evening sky, though you can’t tell with the naked eye. It just looks like a very bright, untwinkling star. In fact, it’s so bright, you might even mistake it for an airplane… Venus has also been mistaken as a UFO.

So the only way you can see the crescent Venus is through a telescope. Any telescope should do. It’ll look like a distant crescent moon. However, because it’ll be so close to the horizon when you see it, you might notice some atmospheric distortion that’ll make it look like a mirage. In my opinion, that’s part of the fun.

Venus has been called Earth’s “Sister Planet,” mostly because it’s about the same size as Earth, and it’s nearby. But it’s in fact a VERY different planet.

You’ve probably heard that its surface is hot enough to melt lead… that’s because of its thick atmosphere that traps the sun’s heat. But there’s other weird stuff going on there too… it has the longest rotation period of any planet in our solar system… 243 days. And it takes about 225 days to orbit the sun. So essentially, its day lasts longer than its year. Oh, and it spins backwards compared to Earth, so the sun rises in the west and sets in the east. And did I mention the sulfuric acid rain?

This weekend, the moon dances between Jupiter and Saturn.

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

Friday and Saturday night, the moon is in the Waxing Crescent phase, but by Sunday, it’ll be a first quarter moon—what some call a half moon.

And a moon with a shadow is so much fun to look at through a telescope. The shadow helps define features like craters and mountains. And because the shadow moves so much from day to day, you can observe every night and find something new.

And while you have your telescope out, you can sweep over to the two best planets to look at through a telescope. Jupiter, and Saturn.

On Friday night, Jupiter will be to the right of and slightly below the moon. It’ll look like a bright white star that doesn’t twinkle. On Saturday, the moon will be a little farther away, almost dead center between Jupiter and Saturn. And on Sunday, the first quarter moon will be right next to Saturn, which looks like a bright yellow star that doesn’t twinkle.

The best time to observe these targets is just after Sundown. Jupiter sets around 10pm, so you’ll need to get out early. Not that you need any help finding the moon, but this weekend it’s in the southern to southwestern sky in the evening.

Look at Jupiter through a telescope and you’ll see its four largest moons flanking the giant planet. Through a large telescope, you may even make out some cloud bands.

Saturn, of course is known for its rings, which you can make out through most telescopes. Larger telescopes will reveal the Cassini Division, or the gap between the two most prominent rings.

So this weekend, take advantage of the clear skies and do a little spying on our celestial neighbors.

I’m Matt Pelsor. Happy skywatching.

We can thank Tropical Depression Gordon for the cloudy, rainy weather this weekend… but if we COULD see the stars, we wouldn’t have any trouble finding this weekend’s target. It’s one of the brightest stars in the sky.

I’m Matt Pelsor, and this is your weekend sky report.

Arcturus has been observed as long as humans have looked up. Ancient Polynesians used it to navigate to Hawaii… Mesopotamians linked it to the god Enlil (EN-lil). Ancient Romans thought the star warned of stormy weather… hmph. It’s even mentioned in some translations of the Bible. Job chapter 38, verse 32 of the King James reads “Canst thou guide Arcturus with his sons?”

If it were clear, you’d find it by looking high to the west around 9pm. Arcturus is a bright orange-white star.

In fact, it’s so bright, it can be observed in the daytime! The French astronomer and mathematician Jean-Baptiste Morin located it with a telescope one afternoon in 1635.

Arcturus is bright for a number of reasons. For one, it’s big. It’s just slightly more massive than our sun, but it’s in a different stage of life… it’s a red giant, which means it’s burned through all of the hydrogen at its core, so it’s 25 times larger than the sun, and 170 times brighter.

It’s also pretty close… less than 37 light years away. This also makes it a popular setting for science fiction. It’s been mentioned in Buck Rogers, Superman, Hitchhiker’s Guide to The Galaxy, and many other stories.

So even if we can’t SEE it this weekend, maybe just knowing it’s there might inspire you to write a little stellar fan fiction.

I’m Matt Pelsor… happy skywatching.