Vénus, the second planet from the Sun, is often called Earth's "sister planet" due to its similar size and composition. It has a thick atmosphere composed mainly of carbon dioxide, with clouds of sulfuric acid, making it the hottest planet in our solar system, with surface temperatures reaching around 900 degrees Fahrenheit (475 degrees Celsius). The planet's surface features include vast plains, highland regions, and numerous volcanoes, some of which may still be active. Vénus rotates very slowly on its axis, taking about 243 Earth days to complete one rotation, while it orbits the Sun in about 225 Earth days.