Portal:Solar System/Selected article/4
Venus is the second planet from the Sun. It is a rocky planet with a mass and size narrowly second in the Solar System to Earth, and with an atmosphere, which is the thickest of all four rocky planets of the Solar System and substantially thicker than Earth's. Its orbit is the next closest to Earth's, orbiting the Sun inferior inside of Earth's orbit, appearing (like Mercury) in Earth's sky always close to the Sun as either a "morning star" or "evening star".
In Earth's sky it is also the natural object with the third highest maximum apparent brightness, after the Sun and the Moon, due to its proximity to Earth and the Sun, its size, and its highly reflective global cloud cover. Because of these prominent appearances in Earth's sky, Venus has been, particularly among the other four star-like classical planets, a common and important object for humans, in their cultures and astronomy.
Venus retains, despite having only a weak induced magnetosphere, an especially thick atmosphere of mainly carbon dioxide, creating an extreme greenhouse effect together with its global sulfuric acid cloud cover. Because of this, the atmosphere reaches at its bottom a mean temperature of 737 K (464 °C; 867 °F) and a crushing pressure of 92 times that of Earth's at sea level, turning the air into a supercritical fluid, though at cloudy altitudes of 50 km (30 mi) Earth like levels are found. Conditions possibly favourable for life on Venus have been identified at its cloud layers, while recent research has found indicative, but not convincing evidence. Early in Venus' history water might have been abundant enough to form oceans, before it probably evaporated when greenhouse effects cascaded and then was taken away into space by the solar wind. Internally Venus is thought to consist of a core, mantle, and crust, the latter releasing internal heat through its active volcanism, shapeing the surface with large resurfacing instead of plate tectonics. (Full article...)