The exoplanet Gj1214b, orbiting the red dwarf star Gj1214 in Ophiuchus, is the first terrestrial planet to have an atmosphere analyzed. This feat was achieved with the ESO-VLT (European Southern Observatory Very Large Telescope) in early 2011. Its transit in front of the star estimated the planet’s mass to be 6.5 Earths, with a diameter of 2.6 Earths. The planet’s atmosphere was determined to be composed mostly of water vapor.
