NASA to Announce New Class of Planets

Astronomers have discovered four new planets in a week's time, an exciting end-of-summer flurry that signals a sharper era in the hunt for new worlds.

Some appear to be noticeably smaller and more solid - more like Earth and Mars - than the gargantuan, gaseous giants identified before.

Planet-hunting is the hottest field in astronomy. This week three teams in the United States and Europe rushed to announce their discoveries of new exoplanets - those orbiting stars other than our sun.

Experts say it won't be long before astronomers detect planets that are similar to Earth's dimensions and characteristics - perhaps even suitable for sustaining life with an oxygen-rich atmosphere and oceans.

NASA to Announce New Class of Planets