VENUS

Venus spins slowly in the opposite direction from most planets. Venus is similar in area and size to Earth, and is sometimes called Earth's "evil twin". Its thick atmosphere traps heat in a runaway greenhouse effect, making it the hottest planet in our solar system with surface temperatures hot enough to melt lead.

Venus is the second planet from the Sun and is often called Earth’s "sister planet" also because of its similar size and composition. However, the two worlds are very different. Venus has a thick atmosphere made mostly of carbon dioxide, with clouds of sulfuric acid, creating an intense greenhouse effect that traps heat and makes Venus the hottest planet in the solar system—surface temperatures can reach around 900°F (475°C). Its atmosphere also creates crushing surface pressure, over 90 times that of Earth’s. Uniquely, Venus rotates very slowly and in the opposite direction of most planets, meaning the Sun rises in the west and sets in the east. One day on Venus (one full rotation) takes about 243 Earth days—longer than its 225-day year. The planet’s surface is rocky and volcanic, with large plains, mountains, and vast lava flows. Because of its brightness, Venus is often visible from Earth just before sunrise or after sunset, earning it the names “Morning Star” and “Evening Star.” Despite its harsh conditions, Venus has been explored by several missions, including NASA's Magellan and the Soviet Union’s Venera landers, with more missions planned to uncover its secrets.