Colonization of Titan Zubrin has pointed out that Titan possesses an abundance of all the elements necessary to support life, saying "In certain ways, Titan is the most hospitable extraterrestrial world within our solar system for human colonization." The atmosphere contains plentiful nitrogen and methane, and strong evidence indicates that liquid methane exists on the surface. Evidence also indicates the presence of liquid water and ammonia under the surface, which are delivered to the surface by volcanic activity. Water can be used to generate breathable oxygen and nitrogen is ideal to add buffer gas partial pressure to breathable air (it forms about 78%
Extraterrestrial atmosphere also been observed in the atmosphere of HD 189733 b, another hot gas giant planet. In October 2013, the detection of clouds in the atmosphere of Kepler-7b was announced, and, in December 2013, also in the atmospheres of Gliese 436 b and Gliese 1214 b. In April 2017, an atmosphere was confirmed around Gliese 1132 b. It is the most Earth-like exoplanet to date that is known to have an atmosphere. In May 2017, glints of light from Earth, seen as twinkling from an orbiting satellite a million miles away, were found to be reflected light from ice crystals in