25 Sep MAPPING OLYMPIC’S SUMMER SKY
Is tonight a clear summer moonless sky? Yes? Then if you’re in Seattle, stand outside at night and look directly above you. If you’re in the dark skies of one of Washington’s three national parks, do the same but just at sunset. This will make it easiest to find Vega, the fifth brightest star in the sky, and the place where we’ll start our mapping journey.
Star charts are difficult. Even when you hold them above your head, their scale is entirely off. Apps are difficult too. There’s so many stars there, often stars you can’t even see with the naked eye, and it’s impossible to tell if you’re lining your phone up correctly with what you’re trying to find. My instructions might possibly be just as helpful as they are–and nothing beats an astronomer pointing the stars out with a laser–but for those of you who thrive on the written word, I hope I can be of some assistance.
In Seattle, and right after sunset in a dark sky, the amount of stars you can see are roughly equal (yes, Seattle’s darkest time of night still has light pollution equivalent to a recently-set sun). Their names are Vega, Deneb, Altair, and Arcturus. The first three form the Summer Triangle.
Keep looking straight up, but now turn your body south. The star you see to the left of Vega is Deneb and to the right is Altair. Deneb makes the tail of the swan Cygnus, otherwise known as the northern cross. You may only see the first star of each wing of Cygnus, particularly if you’re in the city. To find Cygnus’ nose, trace your eyes from Deneb towards the space in between Vega and Altair. That nose is called Albireo, and Albireo isn’t just a star–it’s two!
At the top of Hurricane Ridge, Albireo is the first thing we look at in our telescopes each night, but not for lack of options. Albireo is just one example of an object in the sky that we see as one star but is actually more. In fact, only half the stars you see in even the darkest skies are single stars. The rest are part of systems, orbiting around other stars, close enough you can’t tell them apart.
From here on out, I’ll still be using some of the brighter stars of the sky to help you find your way, but if you’re in a city you probably won’t be able to see them. Get yourself out to the countryside before reading on!
Go back to Vega. Below and a little bit to the right or left of Vega (whether it’s right or left will depend on the time of night and year) are four bright stars that together form a parallelogram (confirm what you see with the image above). Find the two stars of the parallelogram that are furthest from Vega and look right between them. You’re now looking directly at the Ring Nebula. You can’t see it with your naked-eye, but the James Webb Telescope recently look this picture of it:
Is your neck hurting yet? Probably. Are you still facing south? I hope so, because in front of you–if it isn’t too late at night–you should see a twinkling red dot that you might have mistaken as a plane. Just after sunset it’s in the southwest, so look a little to your right. If you were to trace a line between the sky right above you and the horizon, this dot should fall halfway between or lower–the later in the night it is, the closer to the horizon is this dot. It’s a star called Antares, or “the eye of the scorpion”.
Antares is the eye of the scorpion because it’s the brightest star of Scorpius, one of twelve Zodiac constellations. Ever wondered why this constellation was chosen to represent those born in a certain time of year? Well, wonder no longer–this constellation is one of thirteen (Ophiuchus was kicked out of the club because there are only twelve months in a year) that Babylonians realized the Sun passes through at certain times of year, and once upon a time it passed through Scorpius between October 23rd and November 21st.
I say once upon a time because this is no longer the case. The Earth’s rotation has changed since then, and those born between these dates are no longer actually Scorpios. The more you know!
Now look to the left of Antares. Even further left. I promise you’re probably still not looking far enough left–these constellations are a lot bigger than you think. If you can see the Milky Way (it’s that weird, fuzzy, cloudy line stretching over the sky above your head), you want to look at the portion of it directly in front of you. That is the center of our galaxy, and it’s a teapot.
Why a teapot? Well, that’s exactly what the brightest stars of Sagittarius form. If you connect the teapot to Sagittarius’ other, dimmer stars (not traced here), I guess it… kind of… maybe… if you squint… forms the half human-half horse archer of legend. I’m not totally convinced, but whatever.
Below, I’ve traced the teapot Sagittarius on a picture of how it looks in an area with light pollution and in an area without. Notice the two additional objects I’ve labeled.
Mind you, there are many impressive things to see in Sagittarius, but these two are special. The first one, M22 (below), is known as the Great Globular Cluster of Sagittarius. I spent half my summer nights this year looking at it through a telescope and at this point it feels like a good friend.
The other is Sagittarius A*, otherwise known as the supermassive black hole we’re all spinning around. I’d show you a picture but, well. Black on black doesn’t show up on a camera too well.
Are you sick of the south yet? Me too. Let’s turn it around! I need you to spin so that, if you were previously facing 12 o clock, you’re now facing 5 pm. Can you find the Big Dipper?
This iconic arrangement of stars is what we call an asterism. It’s a popular grouping of stars, but it isn’t quite a constellation on its own. It’s part of the constellation Ursa Major, which is (meant to be) a bear. The handle of the Big Dipper is the bear’s tail, while the cup is the bear’s body.
If you locate the three bright stars that make up the handle of the Big Dipper and follow their curve left to the brightest star in the summer sky (and the fourth brightest star seen from Earth), the one that appeared just as Vega did, you would “arc to Arcturus”.
You could continue along that path to “speed on to Spica”, a star in Virgo. But it isn’t just the handle of the Big Dipper that can guide you.
First, look for the two stars in the Big Dipper furthest from its handle. They’ll be the two stars making the very end of the asterism, forming the outside of the dipper’s cup. Once you find it, form a fist with your right hand and then pull your thumb and pinky out of the fist.
Hold your first out away from your face. Put your thumb on the topmost star and angle the rest of your hand so that, if you were to draw a line between the tip of your pinky and the tip of your thumb, it would be at the same angle as a line drawn between the two stars. In other words, you want to extend that line.
If you do everything right, your pinky should land on, or be very close to, another star in the sky. It doesn’t look like much, but its name is Polaris, otherwise known as the north star.
Polaris also forms the end of the Little Dipper’s handle. The Little Dipper is harder to see, especially its cup, but if you have a dark enough sky you’ll notice that the Little Dipper is like the yin to the Big Dipper’s yang.
Now look to the right of Polaris. Do you see a W in the sky, potentially tilted just a little so it looks more like a massive number 3? Yes? Then you’ve found the constellation Cassiopeia. Cassiopeia and the Big Dipper dominate the northern sky in the northern hemisphere all year-round, slowly orbiting true north. In fact, you can even tell what season it is just by looking at either one of them.
Every time I’ve shown attendees of our astronomy program how to find the north star, or ask them if they know how to find the north star, at least one person says they learned of the north star as the brightest star in the sky. This is a myth, which you observed yourself just as the sun went down. If the north star were the brightest star in the sky, it would be the first to appear. On any cloudless night, you would also be able to see it anywhere in the northern hemisphere at any time of year.
In reality, our north star is just another unassuming little dot, but if you keep watching you’ll notice how the northern sky moves in a circle around it. You don’t have to watch for very long. The sky moves much faster than most people think.
Next time you’re at home, step outside on a clear night and find a bright star, preferably one close to a foreground object like a tree or a house. Watch it for about a minute to make sure it’s actually a star and not a plane. If it is a star (or a planet, which look like stars), note in your mind where it is in relation to the foreground object you chose, then use something–tape, a rock, a chair–to mark both where you’re standing and in what direction you’re facing. Return to that spot and turn in that direction 30 mins later. You’ll find that your star has moved quite rapidly across the sky.
What direction your star moved can tell you roughly in what cardinal direction you’re facing too. If the star you chose moved to the right and slightly up, then the direction you’re facing is east (either directly or southeast). If it moved right and slightly down, you’re facing west (either directly or southwest). If it moved only up, you’re facing north and your star of choice is on the right side (in other words, to the east) of the north star. If it moved only down, you’re facing north and your star of choice is on the left side (in other words, to the west) of the north star.
There’s so much to see in the night sky that I could write an entire book on the subject. But the point of this isn’t to overwhelm the casual observer with facts. Just by knowing the brightest objects in the sky, you can figure out where you are on Earth, in what direction you’re facing, and if you get really good you might even be able to figure out what season and time of night it is.
The night sky is, quite literally, a map to guide you–both to where you want to go and what you want to see.
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