By Scott Levine
Some of my favorite conversations about astronomy start with people asking about a group of stars, usually their zodiac sign, and then having a hard time seeing that figure mapped out in the sky.
The word zodiac comes from zoo-, which is the same Greek root that brings us the word for the park with the animals and related sciences.
In astronomy, these are the constellations that we see the sun travel through year after year, and it’s long been seen as the path of life. All but one of these, Libra (the scales), represent a person or a creature of some kind – bulls, rams, twins, fish, you name it.
In July, two of the zodiac’s – and the night’s – most striking constellations come back to the primetime sky.
While many other patterns can leave us scratching our heads – “Really? Those three stars are a ram?” – Scorpius is one that does a pretty good job of looking like the thing it represents. Let’s start with the famous bright red supergiant at the scorpion’s heart, Antares. It’s a truly enormous star, so big and hot that it puts out more than 2,500 times more energy than our sun does.
With all that power behind it, we can still see it as obviously red, even though we’re looking at it across 500-plus light years of space, and through the lingering dusk of another long summer sunset. All month, it’s a stunning sight low in the south as night settles around us.
Once we find it, let’s see if we can make out the small closing parenthesis-shaped group of three stars that represent the scorpion’s head and claws to the right of Antares. Toward the left, the rest of the scorpion’s body fills in, with its tail curling just above the trees and rooftops down the road.
Following right behind it, toward the east, is the constellation-slash-spelling test, Sagittarius. The most prominent part of this group doesn’t look much like the archer it represents, but like a teapot with its spout pointing toward the west and its handle toward the east. None of these are big-name stars – the most famous is called Nunki – but I love that quiet anonymity. There are few things better than seeing these hanging over the hills across the river on another night spent batting away mosquitoes.
Together with Scorpius, a quick glance along the zodiac lets us spend summers laughing at a cartoonish teapot racing and chasing a terrified scorpion across the sky. Who says there’s nothing funny in the sky?
Far behind these is the central part of the Milky Way galaxy, our home in the universe. From our point of view out here in the galactic suburbs, it summers along the eastern horizon from southwest to northeast. It’s tough to see, though. Westchester’s light pollution has pushed the light from those countless stars back, sending them retreating into the night. Under darker skies, we’d see those stars’ light pushed together into a smoky blur, like the light from countless city windows 25,000 light years away.
Night falls late this month, but with the sights in our southern sky’s zodiac, it’s worth the wait. I hope you’ll have a look this month. Clear skies, everyone!
Scott Levine (email@example.com) is an astronomy writer and speaker from Croton-on-Hudson. He is also a member of the Westchester Amateur Astronomers, who are dedicated to astronomy outreach in our area. For information about the club including membership, newsletters, upcoming meetings and lectures at Pace University and star parties at Ward Pound Ridge Reservation, visit westchesterastronomers.org. Star parties are free and open to the public.