Planet Venus is the second planet from the Sun in our solar system. It is similar in size and structure to Earth, often referred to as Earth's "sister planet." Venus has a thick atmosphere composed mainly of carbon dioxide, with clouds of sulfuric acid, making it the hottest planet, with surface temperatures reaching around 900 degrees Fahrenheit (475 degrees Celsius). The surface of Venus is rocky and covered with volcanoes, some of which may still be active. It has no moons or rings and rotates very slowly on its axis, taking about 243 Earth days to complete one rotation. Interestingly, a day on Venus is longer than a year, as it takes about 225 Earth days to orbit the Sun.