NASA Astrobiology : Scientists using NASA’s Hubble Space Telescope have characterized the atmospheres of two of the most common type of planets in the Milky Way galaxy and found both may be blanketed with clouds. The planets are GJ 436b, located 36 light-years from Earth in the constellation Leo, and GJ 1214b, 40 light-years away in the constellation Ophiuchus. Despite numerous efforts, the nature of the atmospheres surrounding these planets had eluded definitive characterization until now. The researchers described their work as an important milestone on the road to characterizing potentially habitable, Earth-like worlds beyond the solar system. Their findings appear in separate papers in the Jan. 2 issue of the journal Nature. The two planets fall in the middle range in mass, between smaller, rockier planets such as Earth and larger gas giants such as Jupiter. GJ 436b is categorized as a “warm Neptune” because it is much closer to its star than frigid Neptune is to the sun. GJ 1214b is known as a “super-Earth” because of its size. Both GJ 436b and GJ 1214b can be observed transiting, or passing in front of, their parent stars. This provides an opportunity to study these planets in more detail as starlight filters ...