Venus is the second planet from the Sun. It is named after the Roman goddess of love and beauty. As the brightest natural object in Earth's night sky after the Moon, Venus can cast shadows and can be visible to the naked eye in broad daylight. Venus has a thick, toxic atmosphere filled with carbon dioxide and it's perpetually shrouded in thick, yellowish clouds of sulfuric acid that trap heat, causing a runaway greenhouse effect. It's the hottest planet in our solar system, even though Mercury is closer to the Sun. The composition of Venus is pretty similar to Earth, with a core of metal, a mantle of liquid rock, and an outer crust of solid rock. Unfortunately, scientists have no direct knowledge about Venus composition. The atmosphere of Venus is the layer of gases surrounding Venus. It is composed primarily of carbon dioxide and is much denser and hotter than that of Earth. The temperature at the surface is 740 K (467 °C, 872 °F), and the pressure is 93 bar (1,350 psi), roughly the pressure found 900 m (3,000 ft) underwater on Earth. In addition to being extremely hot, Venus is unusual because it spins in the opposite direction of Earth and most other planets. It also has a very slow rotation making its day longer than its year. A day on Venus is longer than a year. Venus is hotter than Mercury despite being further away from the Sun. Venus is the second brightest natural object in the night sky after the Moon. Venus is sometimes called Earth's twin because Venus and Earth are almost the same size, have about the same mass (they weigh about the same), and have a very similar composition (are made of the same material). They are also neighboring planets. However, Venus and Earth are also very different. The amount of water in the atmosphere of Venus is so low that even the most drought-tolerant of Earth's microbes wouldn't be able to survive there, a new study has found. Venus not only rotates backwards compared to the other planets, but it rotates very slowly. In fact, a day on Venus (243 days) lasts longer than it takes the planet to orbit around the Sun (225 days). Since Venus and Earth are almost the same size and have about the same mass, the surface gravity on Venus is almost the same as the surface gravity on Earth. The surface gravity on Venus is about 91% of the surface gravity on Earth, so if you weigh 100 pounds on Earth, you would weigh 91 pounds on Venus. Since Venus does not experience rainfall (except in the form of sulfuric acid), it has been theorized that the lightning is being caused by a volcanic eruption. Its cloud layers are packed with sulfuric acid enough to chew through skin, bone and metal in moments. If you stood on the surface, you would escape the corrosive acid rain, but only because rain down there is impossible: the ground bakes at more than 900 degrees Fahrenheit, hot enough to broil any astronaut or robot.