Another Earth

In the sky this week…

  • Jupiter dominates the southern sky during the night.
  • Mars rises around 11 p.m., and Saturn around 3 a.m.
  • Venus might be visible low in the southwest after sunset.
  • Mercury lies low in the east before sunrise.
  • The Moon will be New on December 24.

Ken Tapping, December 21, 2011

In early December, the Kepler satellite, which has so far discovered over 1200 planets orbiting other stars, found a planet that could be like ours. It is just over twice the diameter of Earth, and is the right distance from its parent star to have a comfortable average temperature of about 22 degrees Celsius. Moreover, its parent star is very similar to our Sun, and appears stable and old enough for life to have possibly developed and evolved on the planet. This planet has been designated Kepler 22b. At this point we don’t know much about its atmosphere or conditions on its surface, but additional observations are planned. Kepler 22b lies about 600 light years away. Since a single light year is almost 10,000,000,000,000 km, we will not be in a position to visit for some time.

This diagram compares our own solar system to Kepler-22, a star system containing the first

This diagram compares our own solar system to Kepler-22, a star system containing the first "habitable zone" planet discovered by NASA's Kepler mission. Image credit: NASA/Ames/JPL-Caltech

There are at least two reasons we are really interested in finding life beyond our planet. Firstly, we would like to know that we are not alone in this huge, complicated, and scary universe. Secondly, the universe seems to be tailor-made to produce carbon-based life, like what we have here on Earth, so we would expect it to be present wherever conditions are suitable.

Ken Tapping is an astronomer with the National Research Council's Dominion Radio Astrophysical Observatory, Penticton, BC, V2A 6J9.

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