A National Science Foundation artist's drawing shows the inner four planets orbiting Gliese 581, a red dwarf star just 20 light-years from Earth. The newly discovered planet, in the foreground, has a 37-day orbit and, like Earth, is distant enough from the star for liquid water to exist. Lynette Cook hide caption

itoggle caption Lynette Cook

This artist's rendering shows two Saturn-size planets discovered by NASA's Kepler telescope. Scientists say there is evidence of a third planet, a much smaller one, whose diameter appears to be about 50 percent larger than Earth's. NASA hide caption

itoggle caption NASA

Astronauts will spacewalk on Wednesday in an attempt to fix a broken cooling pump aboard the International Space Station. Though a second pump is currently working, NASA officials are worried about the possibility of it shutting down before the broken pump is fixed. NASA hide caption

itoggle caption NASA

The satellite arrives as a box of little pieces you can configure any way you wish. Alex Antunes hide caption

itoggle caption Alex Antunes