Darkness and light work together in strange ways. The darkest astronomical objects, for example, are black holes -- dense objects with such powerful gravity that not even light can escape from them. Yet black holes power the brightest objects in the universe: quasars.
A typical quasar is hundreds of times brighter than our entire galaxy of hundreds of billions of stars. Yet all this light comes from a region that's no larger than our solar system.
A supermassive black hole sits at a quasar's center. Although the black hole itself emits no light, material falling into the black hole is heated both by friction and by the black hole's gravity. Because this material is so hot, it shines profusely.
The brightest quasar in Earth's sky is in the constellation Virgo. You can see Virgo's brightest star, blue-white Spica, rising above the Moon late this evening.
The quasar is known as 3C 273. Through a telescope, it looks about as bright as Pluto. But while Pluto is just a few billion miles away, 3C 273 is two billion light-years away.
To put that in perspective, imagine that a faster-than-light spacecraft could zip from Earth to Pluto in just one second. At that same speed, the craft would require more than a thousand centuries to reach the quasar.
We can see this distant object only because it's fantastically bright -- a tremendous display of light from the heart of darkness: a supermassive black hole.
Script by Ken Croswell, Copyright 2008
For more skywatching tips, astronomy news, and much more, read StarDate magazine.
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