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Astronomers anticipate 100 billion Earth-like planets in the Milky Way.

Stashed in: Carl Sagan, Space!, Factoids

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The search for intelligent life continues:

“The NASA Kepler space telescope finds Earth-sized planets that are quite close to parent stars, and it estimates that there are 17 billion such planets in the Milky Way. These planets are generally hotter than Earth, although some could be of a similar temperature (and therefore habitable) if they're orbiting a cool star called a red dwarf.”

“Our proposal is to measure the number of Earth-mass planets orbiting stars at distances typically twice the Sun-Earth distance. Our planets will therefore be cooler than the Earth. By interpolating between the Kepler and MOA results, we should get a good estimate of the number of Earth-like, habitable planets in the Galaxy. We anticipate a number in the order of 100 billion.” 

“Of course, it will be a long way from measuring this number to actually finding inhabited planets, but it will be a step along the way.”

The first planet orbiting a Sun-like star was not found until 1995, despite strenuous efforts by astronomers. Dr Yock explains that this reflects the difficulty of detecting from a distance a tiny non-luminous object like Earth orbiting a bright object like the Sun. The planet is lost in the glare of the star, so indirect methods of detection must be used.  

There are 200 billion stars in the Milky Way:

Note that the Milky Way is only one of 200 billion galaxies. Wow.

That means there could easily be 10 thousand billion "Earth-like" planets. And the odds of us finding the few that host life, let alone contacting them, are abysmally low (and especially for contact they are 0).

Where IS everybody?

Zoo hypothesis?

I wonder how many planets satisfy these criteria:

This is the primary literature reference:

"Extending the planetary mass function to Earth mass by microlensing at moderately high magnification..."

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