From Debris to Planets
Scientists learn how things work, in part, by watching them change. A biologist can watch a caterpillar turn into a butterfly. A geologist can watch as a volcano bubbles and explodes. An astronomer can watch a disk of gas and dust turn into a system of planets.
For planets, though, the timescale is so vast that a thousand lifetimes isn't enough to see them take final shape. Fortunately, though, nature provides a way around this limitation. Our galaxy contains lots of star systems that are in different stages of planet formation. So by looking at lots of systems, astronomers can piece together how planets form.
They got several new pieces of the picture a few months ago from the orbiting Spitzer Space Telescope. It found six systems with known planets that are encircled by rings of dust and bigger debris -- the raw materials from which planets form. It's the first conclusive evidence for planets and debris disks in the same systems.
That's important because astronomers believe that planets form from disks of leftover gas and dust encircling newborn stars. The material clumps together into ever-larger bodies, culminating with planets.
The star systems that Spitzer studied are about the same age as our own solar system. They contain a lot more rocky debris than the solar system, but a lot less than young star systems. They may represent a link between newborn solar systems, and more settled ones like our own.
Script by Damond Benningfield, Copyright 2005
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