Brighter Than a Billion Suns

One of the brightest objects in the universe blazes in the constellation of Virgo, the quasar 3C273. Invisible to the unaided eye, it is visible in amateur telescopes even though it is over three billion light years away.

That's quite an amazing thought: it is so bright that for a few hundred dollars, you can buy a little telescope that will show you something a quarter of a universe away.

It - whatever it is - is thousands of times brighter than our entire galaxy, that pinwheel of over a hundred billion stars. What these quasars are -- there are hundreds of them -- is one of the great mysteries of astronomy.

What do we know about it? Not much: it's very far away: three billion light years. But it's also very small. A millionth the size of our galaxy.

How can something so small shine so brilliantly? That's the mystery. Though some questions can be answered right away, others are not so simple. Scientists speculate about them for years before they reach an answer, if they ever do. This is that kind of question.

The leading possibility: at the center of each galaxy there is a supermassive black hole, millions of times larger than our own sun. Gas spirals in to the hole at great speeds. Friction between these streams of gasses heat them to temperatures of millions of degrees, and they emit fantastic amounts of energy. The quasars may be some of these black holes.

This theory is a mixture, a mixture of established fact and speculative ideas. From mixtures like this, science is born.

(3/22/06)