Astronomers discovered
the smallest planet outside our solar system. This is the first that is certainly
rocky like Earth. Measurements of extraordinary precision-called Kepler showed
that 10b is 1.4 times the diameter of Earth and a mass 4.6 times greater than
he. However, because it orbits very close to its star, the exoplanet could not
support life. The discovery has been hailed as "one of the deepest in the
history of mankind."
