Venus is the second planet from the Sun, the closest planet to Earth, and the third brightest object in Earth's sky after the Sun and Moon. Sometimes called Earth's sister planet because their size and mass are so similar, Venus is 7,520 miles in diameter, about 95% the size of Earth, and has gravity that is 90% of what is experienced on Earth. Its surface is hidden by an opaque layer of clouds formed from sulfuric acid, and its atmosphere is 96.5% carbon dioxide with sulfuric acid clouds; at cloud level, about 30 miles above the surface, the atmosphere is about the same as on Earth's surface. Venus spins on its axis in the opposite direction of Earth, and because it takes 225 Earth days to orbit the Sun while completing one very slow backward rotation, it takes 117 Earth days for Venus to experience one day. Formed 4.5 billion years ago when gravity collected swirling gas and dust, Venus, like other terrestrial planets, has a central core, a rocky mantle, and a solid crust. Surface temperatures can exceed 880 degrees Fahrenheit, the planet would appear like a very hazy, overcast day on Earth, and its surface is characterized by tens of thousands of volcanos. The planet is named after the ancient Roman goddess Venus, the goddess of love and beauty.