Weekend Sky Report

The crescent moon is low in the evening this weekend, chasing the sun in the western sky. And as it moves away from the sun in the sky, it becomes more and more illuminated. This weekend it will go from a narrow sliver on Friday night, to a textbook sickle on Sunday night. Each night it will creep higher and higher in the western sky. And any telescope will give you a good view of the moon—even small toy telescopes may surprise you. And crescent moons are great to look at close up because the shadow accentuates craters, mountains, and the so-called “seas.” In fact, Friday night the shadow will reveal one of the best-named seas on the moon. The “Sea of Crises.” Below it, you’ll also be able to see the Sea of Fertility, and the adjacent Langrenus (lang-GREEN-us) crater. On Saturday night, you’ll see part of the Sea of Tranquility, where Apollo 11 landed just shy of 50 years ago. Sunday night reveals part of the Sea of Serenity, and a striking series of craters in the southern hemisphere.

And if you miss it this weekend, don’t worry. The moon will be an evening companion for another couple weeks. The full moon returns July 16th… 50 years to the day since the launch of Apollo 11.

And if you’re looking for more easy targets, look to the southeast for bright Jupiter. It’ll look like a particularly bright star that doesn’t twinkle. Less observant eyes may mistake Jupiter for an airplane. If you have a telescope, you’ll see more moons—Jupiter’s four largest “Galilean moons” Io, Ganymede, Callisto, and Europa.

The stars Vega, Deneb, and Altair form what’s called the summer triangle, which sweeps overhead all night during the warmer months of the northern hemisphere.

Of the three, you’ve probably at least heard of Vega… one of the brightest stars in the night sky. It’s about 2.5 times the size of the sun, twice as massive, and about 40 times brighter. That may sound like it has quite a leg up on the sun, but if you take into account the enormous range in characteristics of stars out there, they’re fairly similar.

Altair is even MORE like the sun. Just under twice the size and mass, and 10 times brighter. Closer than Vega too at less than 17 light years away.

But the REAL star of the summer triangle, if you’ll pardon my unintended pun… is Deneb.

Deneb is an incredible star. It’s a blue-white supergiant. If you were to replace the sun with Deneb, its surface would extend to about Earth’s orbit—we’d be toast. It’s one of the largest known white stars. And, get this, it’s almost 200,000 times brighter. But enormous, energetic stars like this don’t live long. Deneb is only about 10 million years old.

Despite all of that, Deneb is the dimmest of the three stars in the summer triangle. Why? You can probably figure it out. It’s SO far away. About 2600 light years.

The Summer Triangle will be in the eastern sky after sundown. Vega and Deneb form the short side of the triangle with Altair at the point, closest to the horizon.

The summer solstice means the most daylight of the year. It’s great for staying up late, but not so great for astronomy. That combined with the clouds and rain lately have made telescope time a rare treat.

But if you find yourself outside under clear skies, look to the south to find bright Jupiter. Then look to the right for a bright orange star. Antares (an-TEAR-eez) or Antares (an-TAR-eez)… tomato tomato—is a red giant. It’s one of the largest stars we can easily see in the night sky. Even larger than Orion’s Betelgeuse which, if it replaced the sun, would easily engulf the orbits of all four inner planets. Some astronomers believe Antares is so big it could also reach past Jupiter.

Antares got its name from ancient Greek. It essentially means Rival to Mars. Mars is the Roman god of War, and Ares was his ancient Greek counterpart. Ancient astronomers thought Antares with its distinctive reddish hue looked a lot like Mars, but knew the two were different. The word planet comes from the ancient Greek word for “wanderer,” meaning that the stars stayed put while the planets seemed to wander through the sky.

Antares is the heart of the constellation Scorpius. And it’s nearing the end of its life. It’s a particularly massive star, so it will die in a spectacular supernova—possibly within the next 10,000 years. When that happens, Antares will be as bright as the full moon, and easily visible in the daytime.

Father’s Day pairs up with a full moon this year. And if that’s not enough to rile your superstitions, whatever they are, there’s another coincidence on Sunday night… Jupiter will be right next door.

On Sunday, the moon will rise in the southeastern sky just before sundown, which makes perfect sense because when it’s full, it’s opposite the sun from the Earth. Rising just ahead of it is Jupiter, which is bright enough to see even if the sun is out. For your best experience, go out around 10pm. Then the moon and Jupiter will be high enough to the southeast, and the sun will be far enough below the horizon that both will be very easy to spot. Of course, the moon is obvious… it’s… the MOON. Jupiter is that bright, untwinkling star next to it. And Jupiter is in a very special place right now. This past week, it was at opposition, which means the sun, the Earth, and Jupiter are in a straight line. This means it’s at its brightest for the year. But there’s something else at work as well… Every 13 months, the Earth and Jupiter reach a point in their orbits where we’re as close to each other as we can be… less than 400 million miles. That’s quite a coincidence. And it means that Jupiter is about as bright now as it can ever be. So be sure to have a look if you can. A small telescope or even binoculars could show you its four Galilean moons. Normally binoculars wouldn’t be much help to see the moons, but this isn’t a normal time. That said, you’ll definitely have better luck with a telescope.

And don’t worry if you miss it this weekend. Bright Jupiter sweeps across the southern evening sky  all summer.

You don't need anything fancy to enjoy the moon. Even an old toy telescope should give you a surprisingly good view. And never underestimate the power of binoculars either.

This weekend the moon is moving through the waxing crescent phase. It'll be a first quarter moon on Sunday night. A partial moon is so much more fun to look at than a full moon. The shadow accentuates textures. Craters seem deeper, mountains seem taller. And the shadow moves each night to reveal new features. It's easier to appreciate just how big the moon is.

And as you look at it, it's also fun to know what you're looking at. Since the eastern side of the moon will be illuminated, the four easternmost "seas" will be visible all weekend. And I love the names of the moon's seas. There's the the Sea of Fertility to the south, and the Sea of Crises to the north. Further in is the smaller Sea of Nectar, and north of that is the Sea of Tranquility... the landing site for Apollo 11. All four will be visible all weekend, and the northern Sea of Serenity will be visible Sunday night. Also, the south pole is heavily cratered, so there's lots of texture to appreciate there as well.

Look to the western sky in the evening to find the moon this weekend.

If you're more of a full moon person, just wait until Father's Day when the full moon will be low to the southeast, right next to a very bright Jupiter.

We’ve officially called it “Lyra” since the 2nd century when the astronomer and mathematician Ptolemy identified and catalogued it—and it was likely known as Lyra long before the time of Ptolemy. It represents the Lyre of Orpheus from Greek mythology.

To find it, look to the northeast after dark. The REALLY bright star is Vega, which is part of Lyra. But if you’re observing under urban or suburban skies, Vega is probably all you can see. For the rest, you might need binoculars or even a telescope. To see it, look at Vega with binoculars, and then scan down and look for four bright stars below Vega that form an elongated rhombus shape. That’s Lyra… a total of five stars… or six if you count the bright star to the left of Vega.

Now, if you DO have a telescope, there’s a deep sky object hiding in Lyra. The Ring Nebula is one of the best-known planetary nebulas. It was discovered in 1779 by French astronomer Charles Messier, who later added it to his catalogue of comet-like objects. Its official designation is Messier 57. You can find the Ring Nebula between the two stars at the bottom of Lyra. If Vega is at the top, these two stars make up the short side of the rhombus opposite Vega. The Ring Nebula is near the center between those two stars, but you’ll need a decent telescope to see it. For best results, you’ll need at least an 8-inch aperture.

If you see the Ring Nebula, you’ll be looking at the remnant of a red giant which expelled its outer gas layers long ago. Larger professional telescopes can resolve a dim white dwarf at the center, which was the core of the star it came from.

And now for two bright stars... and how to find them. I'm Matt Pelsor, and this is your Weekend Sky Report. Arcturus and Spica are two of the brightest stars in the northern hemisphere, so they're not hard to see... but if you're new to Astronomy, you can use this mnemonic device to find them: Arc to Arcturus, and Spike to Spica. Here's what I mean... First, find the Big Dipper, then follow the curve of the handle, or arc that it makes to bright orange-white Arcturus. From there, continue that same direction, but with a more laser-straight line to bluish white Spica. Arc to Arcturus, then spike to Spica. Arcturus is just slightly more massive than our sun, but it's more than 25 times larger, and more than 150 times brighter. This is because it has entered the next stage of its life... all of its core hydrogen has been used up and it's puffed up to many times its original size. The same thing will happen to our sun in a few billion years. Spica makes up the right hand of the constellation Virgo. In some interpretations, it represents an ear of wheat in Virgo's right hand. It's easily the brightest star in the constellation... and actually, it's two stars. Spica is a spectroscopic binary... meaning it's two stars that are so close together, you can't split them with a telescope. Because they're so close, they orbit each other very quickly. Each orbit takes only 4 days. What's more, the gravitational forces each star has on the other makes them more egg-shaped than spherical. But again, you won't be able to tell that from looking at it through a telescope. When you find Spica, you'll be looking at a star almost 2000 times brighter than our sun. I'm Matt Pelsor... happy skywatching.

Saturday night 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 moon has been pretty elusive over the last few weeks. It’s not only been out at difficult times—the daytime, early morning… but during that time it’s also been small… in the crescent phases the practically invisible new moon…  But now we get a good evening moon back, and it’s in an exciting phase: first quarter—also known to some as a half moon.

And if we’re lucky enough to have clear skies, dig out an old telescope… ANY telescope, or a pair of binoculars to get a closer look. A partial moon is so much more fun to look at than a full moon because the shadow accentuates textured features like craters and mountains. And because the shadow moves every day, it reveals something new each night.

And if you get a chance to look on Friday night, you’ll catch a rare alignment of the moon and the Beehive Cluster, an open star cluster that sits right in the middle of the constellation Cancer. So, depending on when you observe, you may notice dozens of brilliant stars in the background.

If you miss Friday’s show, Sunday night puts the moon right next to Regulus, the heart of Leo the Lion, which is a binary star. After you look at the moon through your telescope, scan over to that nearby bright bluish star and try to split it. With the right magnification, you’ll notice a much dimmer star next to Regulus. That’s two of four stars in that system. If you do get a look at Regulus, remember that it’s a star that spins so fast, it actually looks more like an egg than a sphere.

So welcome the moon back into the evening sky this weekend… and spend a little time with its neighbors too.

When amateur astronomers think of Hercules, they usually think of Messier 13, the brilliant and relatively bright globular cluster near Hercules’ right hip. It’s one you can just about see with the naked eye under perfect conditions… but after you find that one, or maybe instead of looking for that one, use bright Vega and the star Eltanin (el-TAY-nin) to find the slightly dimmer and more distant Messier 92.

M92 is one of the galaxy’s oldest globular clusters. Research published in 2007 suggests it began forming shortly after the Big Bang—more than 13 billion years ago. Globulars take a long time to form, so most of them are some of the oldest structures in the universe, but not many come even close to the age of M92.

To find it, look to the northeast. It’s probably best to look around or after 10pm when bright Vega is high enough above the horizon. Once you find Vega, look above and to the left of Vega for the dimmer, but still prominent orange-white Eltanin (el-TAY-nin). Now, imagine those two stars being part of an acute triangle with Vega at a sharp point. The point opposite Eltanin lies at about the same distance and angle from Vega, but to the right. Point your telescope at that spot and slowly scan upward until you see what looks like a dim, fuzzy star. That’s Messier 92.

Now, despite its proximity to brilliant M13, M92 is still one of the brighter globular clusters in the night sky. So just about any telescope should be able to spot it. And again, when you find it, you’ll be looking at something that began forming just after the dawn of time itself.