NASA's Kepler Spacecraft

As I write this, astronomers know of about 700 planets which lie beyond the solar system. Yet in just 16 months, NASA’s Kepler mission has discovered an additional 2,326 potential new planets. This figure is hitting the mainstream news today thanks to NASA’s announcement that the Kepler space observatory has confirmed the existence of Kepler-22b, a planet which exists within the so-called habitable zone of a yellow G-class star about 600 light years from here.  Kepler-22b orbits its star every 290 Earth days and is reckoned to have an average temperature of about 22 degrees Celsius (approximately 72 degrees Fahrenheit).  Although closer in size to Earth than most exoplanets, the new world still has a radius which is more than twice that of our planet(which means that Kepler-22b’s mass is immensely greater).  Scientists have no idea what Kepler-22b is made of, but because of its high gravity, its atmosphere is likely to be a heavier, sludgier affair than that of Earth.

A Diagram Contrasting the Solar System with Kepler 22-b's Star System (Image credit: NASA/Ames/JPL-Caltech)

The discovery of new worlds is becoming progressively more common–which means that new planets are more difficult to write about (I can testify to this because I have been trying to think of novel and exciting things to say about this new exoplanet). The top google search result for Kepler-22b is currently a smug caricature of the foibles of earthlings.  Within a few days the sparse prose of Wikipedia’s equally scanty entry will probably be the top search result—and that is likely the way that things will remain for a long time (or forever). We are beginning to compile a massive database of different worlds.  As the numbers add up, the true stories will be within the statistical understanding of new planets–unless of course a habitable zone planet leaps out of the news with electromagnetic signatures characteristic of life and intelligence.  That result becomes progressively likely as we begin to learn where to point our telescopes.  Out of the thousands of planets the Kepler mission is finding, Kepler-22b is the first habitable zone world of dozens–or of hundreds.


[Alien clipart by Elizabeth Aragon at]