STEVE INSKEEP, host:
We will continue to bring you the latest on the Tucson shooting, and also keep an eye on other stories around the world. In fact, around the universe. A big hot rock is making news this morning. That's because the hot rock is actually a planet orbiting a star 560 light-years away. It is claimed to be the smallest planet discovered outside our solar system.
NPR's Joe Palca reports.
JOE PALCA: Natalie Batalha is the deputy science team leader for NASA's Kepler space telescope. Astronomers designed Kepler to look for much smaller, solid planets more like Earth. And at a news conference yesterday at the American Astronomical Society meeting in Seattle, Batalha said they'd found one.
Dr. NATALIE BATALHA (Deputy Science Team Leader, NASA Kepler Mission Team): I'm here today to announce the discovery of Kepler's first rocky planet, Kepler-10b.
PALCA: Kepler-10b is only 40 percent larger than Earth. Batalha says Kepler can detect planets like this by measuring the minute decrease in light when the planet passes in front of its star. The dip in light is tiny. Batalha says think of it in terms of light bulbs.
Dr. BATALHA: You've got 10,000 light bulbs and you take just one away - that's the brightness change that we're trying to measure.
PALCA: Actually, Kepler-10b caused its star to dim one and a half light bulbs, but you get the idea. Kepler-10b may be earth-sized and rocky like Earth, but it's not likely to be inhabited. That's because it orbits once every 20 hours, putting it so close to its star that the planet's surface temperature is around 2,500 degrees - a bit toasty for life.
Joe Palca, NPR News, Washington.