Venus is the second planet from the Sun and our closest planetary neighbor. With a radius of 6,052 km, Venus is similar in structure and size to Earth. Venus spins slowly in the opposite direction from most planets. 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. Glimpses below the clouds reveal volcanoes and deformed mountains. Venus is named for the ancient Roman goddess of love and beauty, who was known as Aphrodite to the Ancient Greeks. NASA's Magellan spacecraft orbited Venus 10 August 1990 to 13 October 1994, conducting radar observations of the surface through Venus's thick cloud cover.