Friday, July 30, 2010

100 million Earths and speculation that the Wow! signal was real

Welcome! "Alien Life" tracks the latest discoveries and thoughts in the various elements of the famous Drake Equation. Here's today's news:
g Abodes - A leader of the Kepler planet-hunting team has created a slow-moving scientific stir by telling an audience at a high-tech conference that our galaxy could harbor 100 million Earths, based on the space mission's raw data. The resulting buzz focuses not only on the findings, but also on the means by which they came to light. See article.
g Message - Several times over the past 50 years, searchers have picked up radio signals that flashed once or twice, then disappeared. The best known of these is called the "Wow!" signal, because that's what an astronomer who picked it up wrote on a printout from a radio telescope at Ohio State University in the 1970s. SETI searchers went back to the star in question immediately, but heard nothing. It may be well be, suggests scientist Gregory Benford, that we detected extraterrestrials more than three decades ago — and because we weren't taking into account what E.T. would do, failed to confirm it. See article.
g Cosmicus - A large asteroid in space that has a remote chance of slamming into the Earth would be most likely hit in 2182, if it crashed into our planet at all, a new study suggests. See article.
g Imagining - Want to play the “The Game of Life”? Okay, it’s not really a game. It is an implementation of cellular automata that John H. Conway chose to call "The Game of Life." It simulates the birth, death, etc., of organisms based on certain rules. If you like Tetris, you’ll find the game amusing.

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Pandy said...

That surely has to be a mistake, a gross underestimate!

Kepler only has a 1-in-200 chance of seeing any planet around a star because the exoplanet has to be in an orbit that is oriented just right to cross the host star to be seen at all, from Kepler’s viewpoint.

Therefore if Kepler has discovered 140 Earth sized planets from 1160 observations looking at around 140,000 stars then there are 20 billion Earths (200 x 100 million) in our Galaxy of 100 billion stars.

ie, there is roughly 1 Earth sized planet for every 5 stars

Rob Bignell said...

I agree, Pandy, that Kepler probably is underestimating the number of planets - Earth-sized, Earth-like and in total - across the galaxy. As you pointed out, Kepler can only detect a certain size of planet, meaning anything like Mercury and Mars, moons like Titan and Encelaudus, and even worlds like Pluto, won't be counted. Indeed, in Mars were in a different location in the solar system - say in Venus' orbit, it probably could support life.

At this point, any guestimate at the number of planets is just that - a guess. The positive aspect of the report, however, is that even if it is a conservative estimate, 100 million Earths across the galaxy is a mind-boggling number to everyday Earthlings. It should help reinforce the message that the universe is worth exploring.