Life, the Universe, and Exoplanets

Planets outside our solar system are a hot item these days. Last year the first photos of “exoplanets” were taken. Just last week scientists announced they discovered the smallest exoplanet yet, coming in at just two times the size of Earth, while the week before scientists were even able to predict the weather on one over 190 light years away. The forecast; Sunny with highs over 2200 degrees, lows around 900 or so.

In late December 2006, the European Space Agency launched their COnvection ROtation and planetary Transits satellite, dubbed COROT. Its primary mission: Find planets outside of our solar system. It’s already discovered at numerous planets orbiting far away stars, and its mission has really only begun. NASA’s own satellite, called Kepler, is getting ready for launch in early March that will look for small rocky planets like earth.

COROT finds these planets by carefully observing the light emitted from stars. It focuses on a region of the sky for days at a time and look for any stars that dim ever so slightly because of a planet blocking out some of the star’s light as it passes between it and the Earth. This kind of careful observation can best be done by satellites outside the Earth’s atmosphere. In space stars don’t twinkle, so any stellar dimming is likely because of a transitioning planet, eclipsing the star. Pointing the telescope directly at a star is not a very efficient way to look for planets. The star’s light will overwhelm any that’s reflected off the planet. It would be like looking for a firefly next to a searchlight. It is doable, thats how we were able to take photos of exoplanets, just not very practical.

So where does that leave ET in all of that?

Of course we haven’t been able to find life outside our own planet yet. A team in Britain has put together an estimate of how many intelligent civilizations there may be in our galaxy. Extrapolating data from over 300 planets have already discovered, a team from the University of Edinburgh have estimated there are anywhere between 361 and 38,000 intelligent civilizations in our galaxy. These predictions should be taken with a grain of salt the size of Halley’s Comet of course. There’s no way to tell for sure how widespread life is around the galaxy without leaving our solar system. But the odds look encouraging. Estimates vary but our Milky Way Galaxy is thought to contain roughly a trillion stars. That’s rather a lot of stars, and even if small percentage of them have planets, and a small percentage of those planets have life, that’s still a lot of life in the galaxy. Probably. Hopefully.

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