Tuesday, March 4, 2008

How unlikely is your existence?

from wikipedia:

In astronomy a habitable zone (HZ) is a region of space where conditions are favorable for life as it may be found on Earth. There are two regions that must be favorable, one within a planetary system and the other within the galaxy. Planets and moons in these regions are the likeliest candidates to be habitable and thus capable of bearing extraterrestrial life similar to our own. Astronomers believe that life is most likely to form within the circumstellar habitable zone (CHZ) within a solar system, and the galactic habitable zone (GHZ) of the larger galaxy (though research on the latter point remains nascent). The HZ may also be referred to as the "life zone", "Green Belt" or the "Goldilocks Zone" (because it's neither too hot nor too cold, but "just right"). In our own solar system, the HZ is thought to extend from a distance of 0.95 to 1.37 astronomical units.


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