By Mike Lynch
Where has summer of 2010 gone? I like to hang on to summer as long as I can, and one way to do that is September stargazing. There are still plenty of summer constellations playing on stage in the celestial theater.
As soon as it gets dark, about 8:30 to 9 p.m., the first star that pops out in the east is not a star at all. That’s the planet Jupiter, which is nearing its closest approach to the Earth for 2010 later this month, something astronomers call opposition.
Right now Jupiter is less than 400 million miles away, and through even a small telescope you can see the disk of the largest planet in our solar system and up to four of its moons, which look like little stars on either side of the planet.
As those moons orbit Jupiter in periods of 2 to 17 days, they constantly change positions relative to Jupiter. Some nights you can’t see any of the four moons because one or more of them are either in front of or behind the giant planet.
If it’s clear enough and your scope is up to it, you may even see some of Jupiter’s cloud bands striping the great planet. I’ll have a lot more on Jupiter and its moons later this month.
Far away from Jupiter in the low southern sky is one of my favorite constellations, known by many as the teapot, or more formally Sagittarius, a centaur shooting an arrow at its neighboring constellation to the west, Scorpius the Scorpion.
If you see Sagittarius as a half man-half horse with a bow and arrow, more power to you. I’ll stick with the teapot.
The teapot is also located in the direction of the center of our Milky Way galaxy, a little over 25,000 light-years away. If the sky is dark enough where you are, you’ll see a milky white band of light from the teapot in the southwest sky that runs all the way across to the northeast horizon.
You’re looking at the combined lights of billions of distant stars that make up the main plane of our galactic home.
Nearly overhead is another signpost of summer, the Summer Triangle. Just look for the three brightest stars you can see around the zenith and that’s it. All three stars are the brightest stars in each of their respective constellations.
Vega is the brightest star in the constellation Lyra the Harp. Altair is the brightest in Aquila the Eagle and Deneb is the brightest star in Cygnus the Swan, also known as the Northern Cross.
There’s nothing really all that “summer” about the Big and Little Dippers since they’re visible every night of the year, but summer is a great time to spot them. That’s especially true for the Big Dipper since it’s proudly hanging by its handle high in the northwest.
The fainter Little Dipper is standing on its handle to the right of the Big Dipper with Polaris, the North Star, at the end of its handle.
In the northeast sky look for the sideways W that outlines the throne of Cassiopeia the Queen. Just to the upper left of the queen in the northern sky look for the faint upside-down house with the steep roof which is supposed to be Cepheus the King.
The autumn constellations are on the rise: Pegasus the winged horse, is in the eastern sky after sunset. Look for the big diamond of stars that outlines the torso of Pegasus. This is called the Square of Pegasus, but because of the way it’s positioned in the sky this time of year it’s also known as the Autumn Diamond.
Below and to the left of the Autumn Diamond, scan with a decent pair of binoculars for a faint patch of light. That’s our galaxy’s next-door neighbor, the Andromeda Galaxy, more than 2 million light-years away. One light-year equals almost 6 trillion miles.
Mike Lynch is an astronomer and is author of the book, “Washington Starwatch,” available at bookstores. www.lynchandthestars.com.
The Everett Astronomical Society: www.everettastro.org/.