Venus and Earth are sometimes called sister planets because of their similar size, but don't let this comparison fool you! Venus, the second planet from the Sun, has a thick and heavy atmosphere that traps the Sun's heat to produce sizzling temperatures. This planetary greenhouse has been visited by over twenty spacecrafts. Each mission returned with important data about this mysterious planet.

Image credits: main image, NASA/JPL-Caltech; quote, © AMNH.