Wednesday, March 11, 2009
Our water-covered Earth is drastically different from other known planets. Earth's surface water, land, friendly atmosphere, distance from the Sun, long term stability and a host of other factors have provided an oasis in space that has nurtured microbial life for billions of years and animal life for over 10% of Earth history.
Earth is dramatically different from its neighboring planets but how rare is it among all planets? As we learn more about planets we are finding that they are a diverse set of bodies with complex evolutionary histories. Is it easy to make Earths? How Earth-like does a planet really have to be to support life like us? How long can our planet support animals or even microbial life?
These and similar questions relate to our potential for detecting extraterrestrial life. If life-supporting planets are too rare they will be too far away for detailed study or more fanciful endeavors.
Planets change over time and in the second half of its life, our Earth will become quite "unearthly", an ocean-free body heated by an ever brightening Sun.
How long Earth's plants and animals might survive in this period may depend on the actions and ingenuity of a single species - humans.
The University of Texas at Austin