Portal:Solar System/Selected article/4
Venus is the second planet from the Sun. Similar in size and mass to Earth, Venus has no liquid water, and its atmosphere is far thicker and denser than that of any other rocky body in the Solar System. The atmosphere is composed mostly of carbon dioxide and has a thick cloud layer of sulfuric acid that spans the whole planet. At the mean surface level, the atmosphere reaches a temperature of 737 K (464 °C; 867 °F), making it the hottest planet in the solar system and also a pressure 92 times greater than Earth's at sea level, turning the lowest layer of the atmosphere into a supercritical fluid. From Earth, Venus is visible as a star-like point of light, appearing brighter than any other natural point of light in the sky, as either the brightest "morning star" or "evening star". It was also given the poetic name Ēarendel in Old English, meaning "ray of light" along with the two previous epithets.
Venus orbits closer to the Sun than the Earth does. The orbits of Venus and Earth make the two planets approach each other in synodic periods of 1.6 years. In the course of this, Venus comes closer to Earth than any other planet. In interplanetary spaceflight from Earth, Venus is frequently used as a waypoint for gravity assists, offering a more economical route allowing spacecraft to save fuel. Venus has no moons and a very slow retrograde rotation about its axis, a result of competing forces of solar tidal locking and differential heating of Venus's massive atmosphere. As a result, a Venusian day is 116.75 Earth days long, about half a Venusian solar year, which is 224.7 Earth days long. (Full article...)