Sunday, April 23, 2006

What's That Bright Light in the Sky?

JupiterMost likely, it's Jupiter. The photo to the left is how Jupiter would look tonight as viewed through a fairly powerful telescope. This image is from the wonderful (and free) Stellarium planetarium program.

Night sky showing Jupiter, 8 Lib and 9 Lib

This image shows what you'll see if you look outside at about 1 a.m, looking south from Portland. What's that bright object just below and to the right of Jupiter? Is it one of Jupiter's moons? Nope. That object is really two objects -- 8 Lib and 9 Lib. 9 Lib is a star that is also known as Zubenelgenubi (in Arabic: "Scorpion's southern claw"), located about 77 light-years from Earth. Zubenelgenubi has a close companion star, 8 Lib, and together they appear to be one object in our night sky. In this close-up image you can see 8 Lib and 9 Lib as two separate objects, as well as Jupiter and several of its moons.

Don't have a telescope? That's Ok, as Stellarium allows you to zoom-in on the planets for as close a view as you wish. In this image, we can see Jupiter and three of its moons (Ganymede, Io and Callisto). A really neat feature of Stellarium allows you to select an object and track that object as you zoom forward or backward in time. With Jupiter, for example, you can watch both the planet's rotation and the motion of its moons. Here's a close-up image of Jupiter as it will appear in one month, with its moons Europa (to the left) and Callisto (to the right).

Here's an image of the night sky (looking south) in one month (on May 24th). Notice how Jupiter has moved around to the right of Zubenelgenubi. And finally, a special treat: Here's an image for May 12th, in which you'll see Jupiter, Zubenelgenubi and a full Moon.

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