Snakes on a (Galactic) Plane

While we’re waiting for the IAU to decide on the latest planet definitions, let’s turn our attention to a pair of constellations that lie in the southern part of the northern hemisphere sky at this time of year (mid to late summer): Ophiuchus and Serpens. They both lie near the plane of the galaxy, and believe me, finding a play on the words in the name of a popular movie and relating it to astronomy has been bugging me for days!

So, work with me here. It’s been a long, hot summer. You wanna see some other kinds of snakes on a plane? Step outside tonight, face south and look around for the familiar teapot of Sagittarius or the S-shaped sweep of Scorpius. Ophiuchus is just above the heart of the Scorpion, the red star Antares.

Courtesy of StarrySkies.com (and a link to a fine, large sky chart).
Courtesy of StarrySkies.com (and a link to a fine, large sky chart).

This chart shows you the general outlines of Ophiuchus and his ophidian companion. One half of the snake (Serpens Cauda) points toward Aquila the Eagle (with the bright star Altair), and the other half of the snake (Serpens Caput) points toward Corona Borealis (the northern crown).

So, that’s the snake part. To get the plane part, just scan the sky with binoculars (or your naked eye if you happen to have good dark skies) and you’ll be looking at the plane of the Milky Way, and in particular, you’ll be looking toward the center of our galaxy. What more could you ask for, and it’s not even scary!

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