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Lots of Planets

March 9, 2013

The discovery of a new “exoplanet” doesn’t generate a lot of excitement these days. That’s because astronomers are discovering planets in other star systems at an astonishing pace. The number of confirmed planets is getting close to a thousand. And just a couple of months ago, scientists with the Kepler mission announced the discovery of almost 500 more possible planets. Astronomers will use ground-based telescopes to try to confirm the discoveries.

Today, much of the excitement isn’t over individual new planets. Instead, it’s about what the large numbers reveal about how all planets form - and what percentage of planets might be suitable for life.

One thing the numbers tell us is that planets like to move around. Many planets are so close to their parent stars that they must have been born much farther out and then migrated inward. The planets might move inward as the result of friction with gas and dust leftover from the birth of the planets, or through gravitational interactions with other planets.

How many planets are suitable for life is still uncertain. A habitable planet would have to be at the right distance for liquid water, and it would have to be small and rocky, like Earth. Searches haven’t revealed many worlds that fit that profile. In part, though, that’s because it takes longer to find such worlds.

But it should be easier to find habitable worlds around one particular class of stars. More about that tomorrow.


Script by Damond Benningfield, Copyright 2013

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