Other than its atmosphere, Venus is so similar to Earth that it is sometimes called Earth's sister planet. Its diameter and mass are almost identical to Earth's. Why, then, is it so hot?
The "greenhouse effect" on Venus is caused by its atmosphere. Energy from the Sun passes through the atmosphere to the planet's surface, where it is absorbed and reradiated at longer wavelengths (as heat). Venus' atmosphere traps these longer wavelengths so they cannot escape …show more content…
Daytime on Venus is about as bright as a cloudy day on Earth, and the winds on the ground are gentle. Gravel and flattened boulders are scattered over the plains. Because of the heat and pressure on Venus, no probe landing there has ever survived for more than an hour.
More recent radar observations by the Magellan spacecraft have allowed scientists to peek through the clouds and map almost the entire surface of the planet. Magellan discovered mountains on Venus that are higher than any on Earth, as well as a valley that is longer and deeper than the Grand Canyon. It also revealed that the surface of Venus may contain active volcanoes, which occasionally vent molten rock and gas into the hellish atmosphere.
Because of Venus' heavy atmosphere, the planet's surface pressure is very high. Pressure is defined as the weight of the atmosphere pressing down on you. On Earth, we don't notice the air pressure at all. The thick atmosphere on Venus would make it difficult to see objects very far away from you.
Since carbon dioxide is poisonous to humans, you would not be able to breathe on Venus. Thick, high clouds would make the Sun just a yellow-orange smear of light, if it was visible at all.
Although the gravity