which planet is most similar in temperature to earth
Earth analog Scientific findings since the 1990s have greatly influenced the scope of the fields of astrobiology, models of planetary habitability and the search for extraterrestrial intelligence (SETI). NASA and the SETI Institute have proposed categorising the increasing number of planets found using a measure called the Earth Similarity Index (ESI) based on mass, radius and temperature.[4][5] According to this measure, as of 23 July 2015, the confirmed planet currently thought to be most similar to Earth on mass, radius and temperature is Kepler-438b.[6] Scientists estimate that there may be billions of Earth-size planets within the Milky Way galaxy alone.[2][7]
Climate of Mars Some scientists maintain that the great mass of the Tharsis volcanoes has had a major influence on Mars's climate. Erupting volcanoes give off great amounts of gas, mainly water vapor and CO2. Enough gas may have been released by volcanoes to have made the earlier Martian atmosphere thicker than Earth's. The volcanoes could also have emitted enough H2O to cover the whole Martian surface to a depth of 120 m (390 ft). CO2 is a greenhouse gas that raises the temperature of a planet: it traps heat by absorbing infrared radiation. So Tharsis volcanoes, by giving off CO2, could have made Mars more Earth-like in the past. Mars may have once had a much thicker and warmer atmosphere, and oceans and/or lakes may have been present.[10] It has, however, proven extremely difficult to construct convincing global climate models for Mars which produce temperatures above 0 °C at any point in its history,[11] although this may simply reflect problems in accurately calibrating such models.