Portal:Solar System/Selected article/4
Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet, being orbital neighbours as well as Venus having the most similar mass and size to Earth among the planets of the Solar System. While both are rocky planets, Venus has an atmosphere much thicker and denser than Earth and any other rocky body in the Solar System. Its atmosphere is composed of mostly carbon dioxide (CO2), with a global sulfuric acid cloud cover and no liquid water. At the mean surface level the atmosphere reaches a temperature of 737 K (464 °C; 867 °F) and a pressure 92 times greater than Earth's at sea level, turning the lowest layer of the carbon dioxide atmosphere into a supercritical fluid.
Venus is the third brightest object in Earth's sky, after the Moon and the Sun, and, like Mercury, always appears relatively close to the Sun, either as a "morning star" or an "evening star", resulting from orbiting closer (inferior) to the Sun than Earth.
Compared to the other planets of the solar system, the orbit of Venus is relatively close to the orbit of Earth. Therefore, for spacecraft traveling from Earth, Venus has the lowest delta-v compared to the other planets and is often used for gravity assists and as a common waypoint for interplanetary flights from Earth. Venus and Earth stay on average to each other the second closest planets, with only the most inferior orbiting Mercury staying closer to all the Solar System planets. Venus and Earth approach each other in synodic periods of 1.6 years. The rotation of Venus has been slowed and turned against its orbital direction (retrograde) by the currents and drag of its atmosphere. A Venusian day is 116.75 Earth days long, about half a Venusian solar year, which is 224.7 Earth days long, and has no moons. (Full article...)