Atmosphere of Venus
The gaseous envelope surrounding Venus, composed mainly of carbon dioxide and marked by extreme pressure, heat, and sulfuric-acid clouds.
Runaway greenhouse effect: A climate feedback in which warming increases greenhouse trapping until a planet reaches a much hotter state. Carbon dioxide traps enough heat to keep Venus’s surface near 465 °C.
Carbon dioxide: A colorless gas composed of one carbon atom and two oxygen atoms that absorbs infrared radiation. It makes up about 96.5% of Venus’s atmosphere and drives strong heat retention.
Pioneer Venus: A NASA mission that studied Venus with an orbiter and atmospheric probes from 1978 onward. Its probes directly measured atmospheric composition, pressure, and temperature during descent.
Earth's atmosphere: The gaseous envelope surrounding Earth, composed mainly of nitrogen and oxygen. Unlike Earth’s atmosphere, Venus’s is overwhelmingly carbon dioxide and far denser at the surface.
Phosphine on Venus: A disputed claim that phosphine gas is present in Venus’s atmosphere, based on contested spectral measurements. The proposed detection raised questions about cloud chemistry and possible biological sources.
Venusian superrotation: The rapid atmospheric circulation that carries Venus’s clouds around the planet far faster than the surface rotates. Winds near the cloud tops circle Venus in about four Earth days.
Sulfuric acid: A strong mineral acid with the formula H₂SO₄, formed in Venus’s atmosphere from sulfur compounds and water. Droplets of it compose the planet’s persistent cloud layers.
Venera program: A Soviet series of missions that explored Venus with flybys, orbiters, landers, and atmospheric probes. Venera landers returned measurements from the crushing surface environment.
Atmosphere of Mars: The thin gaseous envelope surrounding Mars, composed mainly of carbon dioxide. Mars shares Venus’s dominant atmospheric gas but has much lower pressure and weaker heat retention.
Venusian cloud chemistry: The chemical reactions and particle processes that determine the composition and behavior of Venus’s clouds. The clouds contain unexplained ultraviolet absorbers and incompletely understood sulfur chemistry.