Venus is, in many respects, the twin of Earth. These outward similarities led some to believe that Venus was a hospitable planet, where jungles and dinosaurs could be found. Sci Fi magazines featured interesting covers illustrating the stories inside. We sure made some very odd movies about Venus. But, a closer look at Venus shows that it is in no way an identical twin of Earth. The conditions on its surface are brutal! The atmospheric pressure at the surface is ninety times greater than Earth’s and the surface temperature hovers at about 730 Kelvin (457 Celsius) most of the time. There has never been a break in the clouds of Venus which rain down sulfuric acid to near the surface as virga. With no plate tectonics, most of the surface is similar to the basaltic floors of Earth’s oceans, but without the water. A global map of the topography shows little change in elevation. For reference, here’s a look at Earth’s topography. A number of space probes from the former Soviet Union and the United States have gathered data which give us an entirely different view of Venus. We have hundreds of images from these probes. All of which show a barren and inhospitable surface.
The radius of Venus is 6,052 kilometers, which is only slightly less than Earth's. This smaller size, along with slightly less mass makes the surface gravity of Venus 90% of Earth's. If you walked around on the surface, you might not notice the difference.
First of all, Venus rotates backward, or retrograde, unlike any of the other terrestrial planets. It take 243 days to spin once, which is sometimes expressed as -243 days. The time from noon to noon, or the synodic day, is 117 of our Earth days.
Venus' orbit is a little less than 3/4 of the size of Earth's. It orbits the Sun in just about 225 of our days. That would be the length of the year on Venus. Venus' orbit is one of the most circular in the solar system with an eccentricity of only 0.0067.
The atmosphere of Venus does not smell very good. It is 95% carbon dioxide, and a few percent nitrogen. But it is the sulfur dioxide which gives the planets its wonderful rotten egg smell. The pressure at the surface is 92 bars with just the slightest wind.
Of course Venus has clouds! There’s always clouds on Venus. We have never seen the surface from Earth. We believe there is a level in the clouds which is about eaqual to Earth’s atmospheric pressure and temperature. Perhaps we could float there in a big balloon and explore the planet from above.
Venus has no moons. Although discovering one might be Neith.