The teapot is ‘steaming’ with stars
This week in Starwatch I want to take you to the low southern skies for one of the best constellations of summer, Sagittarius the Archer, one of the zodiac constellations.
Not only is Sagittarius easy to find in our Butler skies, it’s also in the direction of the center of our Milky Way galaxy, home of our sun and at least 100 billion other stars, with even more planets, some, maybe just like our Earth.
As soon as it’s dark enough, around 9:30 p.m., look in the low southern sky just above the horizon. You want to make sure your view is fairly unobscured with a low tree line. An open field is best.
Look for a distinct pattern of eight fairly bright stars that clearly outline a teapot. Unless it’s really light-polluted where you are, it should be very easy to see. There are four stars on the left-hand side that make up the handle, three stars on the right that make up the spout, and one in between that marks the top of the teapot’s lid.
That celestial teapot in the low southern sky isn’t officially a constellation, but it’s what astronomers call an asterism, a very easy-to-see pattern of stars that isn’t officially a constellation. Our teapot asterism is actually the brightest part of the official constellation Sagittarius the Archer.
One of the many stories about Sagittarius has its roots in Greek mythology. Sagittarius is supposed to outline a centaur shooting an arrow. In case you’ve never run into one, a centaur is a mythological creature with the head, arms and torso of a man and the body and legs of a horse.
With a slight overload of imagination you may be able to see how the teapot asterism could outline the upper body of the centaur shooting an arrow. The handle would outline the bent arm of the shooting centaur and the spout would be the bow and arrow ready to fire.
In Greek mythology, centaurs had a nasty reputation. They were deceptive, despicable characters who drank too much and got into a lot of fights. They had no tolerance for anyone who wasn’t their kind.
According to legend though, there was one well-behaved centaur named Chiron who was well-educated and had some manners. He stayed out of the bars and preferred hunting for quail on his farm. Unfortunately, Chiron was accidentally killed by the great hero Hercules, whose constellation is also part of the summer sky.
According to this classic epic, Hercules was taking on a battalion of rioting centaurs who were attacking him. Hercules fought them all to the death one by one and was riding off when he spotted another Centaur in the distance. This was Chiron, who just happened to be passing by on his way back from the library. Hercules, still emotionally heated up from his tumultuous struggle, figured Chiron was just another hostile Centaur and hurled a spear at the gentle half-human-half-horse, doing him in.
Gentle Chiron was a favorite of the leading gods of Mt. Olympus, and when he got knocked off by Hercules, they felt sorry for him and placed his body in the sky in the form of the constellation we still see in the summer.
It’s really great this time of year if you can get out to the countryside and stargaze away from city lights. In dark summer skies, it looks like the teapot is steaming. That “steam” is actually the combined light of billions of stars that make up the center of our galaxy.
You can also see, without a doubt, a bright “milky” band that runs from the teapot’s steam and stretches all the way across the celestial dome toward the Northern horizon. That’s the combined light of billions and billions of stars that make up part of the disk of our Milky Way. Now, our sun and every single star we see in our night sky is also part of the galactic disk, but relatively close by.
The center of our galaxy, above the teapot’s spout, is about 26,000 light-years away. (By the way, just one light-year is almost 6 trillion miles!) The downtown section of our home galaxy would appear a lot brighter in our sky, but there’s a lot of obscuring interstellar gas and dust in the way. Many astronomers believe that if it weren’t for all that gas and dust, the part of the sky around Sagittarius would be brighter than the full moon.
Nonetheless, that part of the Milky Way band around the teapot is still fairly bright and loaded with a lot of celestial treasures. Even with a small telescope or a pair of binoculars you’ll find many many star clusters and nebulae.
With a telescope, look just above the teapot’s spout into the steam puff and you’ll have a good chance of spotting Messier Object 8, or M8, the Lagoon Nebula. It’s a bright emission nebula where stars are being born. Even a small telescope gives you a great view.
This giant cloud of hydrogen, the raw material from which stars are manufactured, is around 5,000 light-years away and roughly 100 light-years in diameter. Within this cloud, many new, very energetic stars are being gravitationally born, lighting the nebula like a huge fluorescent light.
It’s too bad that Sagittarius is so close to the horizon in our part of the northern hemisphere, because our view of all these celestial goodies isn’t as clear as it could be. We’re forced to view them through a thicker layer of Earth’s atmosphere, and if there’s any extra humidity in the air that makes it worse. Even with all that, it’s still rewarding to scan the sky for a celestial arrow-shooting centaur.
If you ever get a chance to see Sagittarius closer to the equator — in places like Central America or even in the southern hemisphere — the view of Sagittarius and its vicinity will be beyond awesome! That’s definitely on my bucket list.
Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul. He is also the author of “Stars: a Month by Month Tour of the Constellations,” published by Adventure Publications and available at bookstores and at adventurepublications.net. Contact him at mikewlynch@comcast.net.
