The extrasolar planet, or exoplanet, GJ 1214b was discovered last year orbiting a dim, red star about 40 light-years from Earth. The planet is about 2.7 times larger than Earth and about 6.5 times more massive.

Based on the planet's density, astronomers estimate that GJ 1214b would be about three-quarters water with a solid core and an atmosphere—not unlike Earth.

But it seems the similarities stop there. The planet is so close to its star that any water would be turned to vapor, and the atmosphere should be so thick that the pressure would be immense.

Now new measurements show that GJ 1214b's atmosphere is made of either dense, ultrahot steam or