Venus is the second planet from the sun, and is about the same size as Earth. It is a terrestrial planet, meaning it has a solid surface. But the harsh conditions on Venus make it very inhospitable. Two spacecraft, Pioneer Venus 1 and Magellan, were able to penetrate the thick atmosphere of this planet. They learned that the atmosphere is mostly poisonous carbon dioxide and that fierce winds push yellow clouds of acid across the planet surface.
When we see the "morning star" or the "evening star," we are generally looking at Venus. Its bright, beautiful white light inspired its name. Venus is the Roman goddess of love and beauty. What ancient people didn't know when they gave the planet its name was that the beautiful light we see in the sky was being reflected from the cloud tops of a deadly, violent world. We know some things about Venus from radar mapping that has been done at a safe distance from its surface. The Magellan spacecraft that visited Venus gave us the most detailed information we have about this dangerous planet.
Venus has many craters and canyons on its surface. The troughs on the planet are part of a system of canyons, or "chasma," that is more than 4,000 miles long. There are many volcanoes on Venus but scientists don't know if any of them are still active. The Howe Crater is a little more than 23 miles in diameter. Unlike our moon, which has thousands of small craters, most craters on Venus are large.
During the day, temperatures reach almost 464 Celsius, 900 Fahrenheit, making Venus the hottest planet in the solar system. Although Mercury, which is closer to the sun, Venus is hotter because of its thick atmosphere of gases, which Mercury does not have. Venus is an example of the greenhouse effect on a planetary scale. The atmosphere of Venus is made up almost entirely of carbon dioxide. Once heat from the sun gets to the surface of the rocky planet, a lot of it is trapped there. This means that Venus, which is similar to Earth in size, is an extremely hot planet.
Also, the thickness of Venus's atmosphere means that if you could stand on the surface, the pressure would be like being a kilometer deep in the ocean. Its air pressure is 90 times greater than Earth's. Because of the combination of heat and pressure, the few Russian spacecraft that landed on its surface were quickly melted and crushed. Fortunately, they did manage to survive long enough to send back a few images of this heated world.
Smaller objects are likely burned up in Venus's thick atmosphere before they reach the surface. A day on Venus lasts longer than a year on Venus. It takes Venus 243 Earth days to rotate once on its axis, but only 223 Earth days to revolve once around the sun. Another peculiarity of this planet is that it rotates from west to east. On Venus, the sun rises in the west and sets in the east. Nevertheless, Venus is considered Earth's sister planet because it is closest to Earth and is a similar size.