Venus: Structures & Vocabulary

Venus is nearly Earth's twin in size and bulk density but radically different at the surface. It has a dense carbon-dioxide atmosphere, global sulfuric-acid cloud cover, surface pressure around 90 bars, temperatures hot enough to melt lead, and widespread volcanic and tectonic landforms hidden beneath the clouds.

A powerful greenhouse effect traps outgoing infrared radiation and keeps the lower atmosphere extremely hot. With little surface water and no Earth-like plate tectonics, Venus loses one major pathway for cycling carbon into rocks. Mantle convection and volcanism continue to reshape the crust, while the dense atmosphere transports heat efficiently around the planet.

Radar mapping from spacecraft such as Magellan penetrated the cloud cover and revealed lava plains, volcanoes, coronae, ridges, and impact craters. Soviet Venera landers measured surface conditions directly, while spectroscopy established the atmospheric composition and cloud chemistry. Crater statistics suggest much of the surface is geologically young compared with the age of the planet.

The atmosphere is mostly carbon dioxide with nitrogen and trace gases, capped by sulfuric-acid clouds. The rocky surface contains volcanic plains, highlands, fractures, and large volcanoes. Venus rotates very slowly and retrograde, has no Earth-like plate-tectonic system known today, and lacks a strong intrinsic global magnetic field.