Venus is the second planet from the Sun and is often called Earth’s twin due to its similar size and mass. It is the hottest planet in our solar system, with surface temperatures hot enough to melt lead, averaging around . The planet has a thick, toxic atmosphere composed mainly of carbon dioxide, with clouds of sulfuric acid. Uniquely, Venus rotates in the opposite direction of most planets (retrograde rotation) and has no moons. It is also the brightest natural object in the night sky after the Moon.