The Milky Way: not just a candy bar

Heymatt:

I live in the Jamul darkness, and I was wondering why the Milky Way is always in view? Same place, any season, never changes. Have any ideas?

-- Lions Peak Lookout

I sure do. We can't avoid the Milky Way because we happen to be inside it. Everywhere we go, there it is. It might look like a broad band of stars running across the sky, but it's actually a huge, spinning, spiral galaxy-- biw-yons and biw-yons of stars and planets and space dust. Our solar system is a tiny dot on one of the curved arms that branches off the center. To put it another way, the shape of the Milky Way has been compared to two fried eggs back-to-back. We're embedded in the egg white, somewhere near the outer edge, slightly above the equatorial plane of the formation.

Because of the seasonal motion of the Earth, the location of the Milky Way does change in the sky if you follow it closely through the year. But because it contains so many stars, it's hard to identify exactly what part of the Milky Way you're seeing at any given time. The Milky Way happens to be part of a cluster of 33 galaxies, all moving in unison through space.

If you don't already, you should consider yourself very lucky, Mr. Lookout. NASA estimates that two-thirds of the world's population is not able to see the Milky Way at all because of urban light pollution. If you're in that two-thirds, it's worth a trip to some desolate place (try a mountain peak in the Rockies) to see the Milky Way and the rest of the night sky. For something around us all the time, we hardly see any of it usually. Just a few bright stars and planets and a lot of blackness. You'll be amazed at what else is up there.