Planetary Gem

Looks like there's a diamond in the sky - possibly the equivalent of three Earth masses. Yale astrophysicist Nikku Madhusudhan reports that a planet about 40 light-years away likely has a diamond layer nearly 2,500 miles thick, topped by a graphite surface. Called 55 Cancri e, the carbon-rich orb has little water and is fiery hot, at around 3,900 degrees Fahrenheit. "Scientists often assume that rocky planets are oxygen rich, like Earth," says Madhusudhan, who analyzed the planet's measurements. "This shows what extreme diversity can be out there."