Characteristics of Venus
Written by Fraser Cain
Venus. Credit: NASA
Venus is the second planet from the Sun, and considered in many ways to be a twin planet of Earth. It has a similar size, mass, density and gravity, as well as a very similar chemical composition. In other ways, Venus is very different than Earth, with its high surface temperature, crushing pressure, and poisonous atmosphere. Let's take a look at some of the characteristics of Venus.
As I said at the beginning, Venus is the second planet from the Sun. It orbits at an average distance of 108 million km from the Sun, taking almost 225 days to complete one revolution around the Sun. One of the strange characteristics of Venus is that it's actually rotating backwards from the rest of the planets. Seen from above, all of the planets rotate counter-clockwise, but Venus turns clockwise on its axis. Even stranger, a day on Venus lasts 243 days, which is longer its year.
In terms of size, Venus is quite similar to Earth. Its radius is 6,052 km (95% the size of the Earth). Its volume is about 86% the volume of Earth, and its mass is 4.87 x 1024 kg, which is about 82% the mass of the Earth. The gravity on Venus is 90% the gravity on Earth, so if you could actually walk around on the surface of Venus, the gravity would feel very similar to Earth.
It's when you get to the atmosphere of Venus that you see that the planet is very different from Earth. The temperature on the surface of Venus is a blistering 462 °C. That's hot enough to melt lead! Furthermore, the atmospheric pressure on the surface of Venus is 92 times Earth pressure. You would have to travel a kilometer down beneath the surface of the ocean on Earth to feel that kind of pressure here. Venus' atmosphere is composed almost entirely of carbon dioxide (97%), and it's this thick atmosphere that acts like a blanket, keeping Venus so hot.
Venus has no water on its surface, and very little water vapor in its atmosphere. Scientists think that the runaway greenhouse effect that makes Venus so hot today boiled away its oceans long ago. Since Venus lacks a planetary magnetic field, the Sun's solar wind was able to blast the hydrogen atoms out of Venus' atmosphere and into space. Venus can never be cool again.
Most of the surface of Venus is covered by smooth volcanic plains, and its dotted with extinct volcanic peaks and impact craters. Venus has much fewer impact craters than other planets in the Solar System, and scientists have estimated that some event resurfaced Venus between 300-500 million years ago, wiping out all of the old impact craters and volcanoes.
Venus has no moons or rings.
We have written many articles about Venus for Universe Today. Here's an article about Venus' wet, volcanic past, and here's an article about how Venus might have had continents and oceans in the ancient past.
Want more information on Venus? Here's a link to NASA's World Book on Venus, and here's NASA's Solar System Exploration Guide to Venus.
We have recorded a whole episode of Astronomy Cast that's only about planet Venus. Listen to it here, Episode 50: Venus.
Filed under: Astronomy
