Field of Science

This Neighborhood Is Getting Crowded

In 1988 exactly one (1) extrasolar planet was thought to exist, and that was confirmed in 1992.  So that's a total of 10 planets, nine (before Pluto got demoted) orbiting an undistinguished, medium-sized yellow star, which the carbon-based, primate-descended inhabitants of the third planet call Sol, and one planet orbiting another star.  Now there are 837 known extra-solar planets (as of 15 September 2012) in 660 planetary systems.  Based on what is now known, each star in the Milky Way galaxy (by the way, galaxia mean milky), which has a 100 billion stars, give or take, is now estimated to have an average of 1.6 planets, or a galaxy with 160 billion planets.  Something like 2400 possible planets await confirmation (presumably very detailed measurements).  Doc Madhattan posts a nice video of how planets form and most interesting is the significance of the ice line.  So doesn't it seem like the galactic neighborhood is getting a bit crowded?  After all it was just about 500 years ago when we thought Earth was the center of the universe.  20 years ago we knew about one additional planet, and now we probably know about 2400 planets.  The nearest known planet orbiting Epsilon Eridani is only 10.5 light-years away (approx. 63 trillion miles)!  TPP will be closing his window shades at night. 

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