What the center of the galaxy looks like

The Milky Way galaxy is a collection of hundreds of billions of stars. This island of stars contains our sun and planets. Astronomers have estimated that the total luminosity of the central dozen or so light-years of our galaxy is equal to about 10 million suns. That sounds big and bright – until you recall that the center of our galaxy is 25,000 light-years away.

At that distance, if interstellar dust weren’t in the way, our unaided eyes would see the central part of our Milky Way galaxy as a central glow no bigger than the planet Venus, and no brighter than one of the stars of the Big Dipper.

Interesting … but not blazingly bright. But wait. There’s more.

The fact is that interstellar dust obscures more than just this central region. It also dims the light of billions of foreground stars, as well as stars surrounding the core itself.

If there were no dust between us and the galactic center, the light of all the stars located toward the galaxy’s core would easily exceed that of a full moon. If you looked in that direction, you wouldn’t see much else but the combined glow of billions of stars.

Our thanks to:
Michael Rich

David Spergel
Princeton University

Mark Morris

March 9, 2008

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