Tuesday, February 3, 2009

Earth-like Planet Found Orbiting Sun-like Star

This is big news, people!
I'm planning a lengthy post on the subject of exoplanets eventually because it is one of my favorite topics in astronomy. However, with this breaking news just released, I have to fill you in a bit now.
For the last 15 years or so, we've been able to detect planets orbiting stars that are not our Sun. We call them extrasolar planets, or exoplanets for short (meaning when we're too excited to actually say the full name because what we're about to say about them is just too amazing). However, the vast majority that we have found are much larger than Earth; most are in the magnitude of Jupiter, which could fit 1,300 Earths inside it. This is not because most exoplanets are huge; instead, it's because our technology is still limited at this time and we can only detect really massive exoplanets.
That said, technology in this field has dramatically improved in the last decade plus and we are detecting smaller and smaller worlds. In fact, we have detected 336 planets orbiting 285 stars to date. This number will only increase exponentially as we continue to develop more precise and more sensitive equipment.
Today's announcement is really big news. The COROT space telescope has identified a small (less than twice the size of Earth) planet orbiting a sun-like star. We've never seen that before (outside our solar system). Early data suggests that it may well be a rocky planet like Earth, as opposed to a gas giant like most other exoplanets detected to date.
One of the biggest differences between this planet, called COROT-Exo-7b (gotta love those super-creative astronomers!), and our home world is that it is very close to its host star. In fact, its year is about 20 Earth hours. To put that in perspective, Mercury takes about 3 Earth months to orbit the sun. The close proximity to its host star makes this newly discovered world's temperature range from 1,000 to 1,500 degrees C. I'll never complain about South Florida summers again. OK, I might.
This system is 457 lights years from Earth, and COROT-Exo-7b is the first Earth-like exoplanet discovered using the transit method. If that doesn't make sense to you, good! It means you'll just have to check back for more sciency goodness.

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