The size of a planet is measured in many ways: mass, volume, equatorial diameter, and surface area are the most common. In this article we are going to explore each of these ways to express the size of Venus and a few interesting facts about our close neighbor.
Venus has a diameter that is about 95% of Earth’s. It is 12,100 km across. The Venusian surface area is around 90% of our own at 4.6×108 km2. The planet has a volume of 9.38×1011 km3. That puts it a little over 85% of Earth’s volume. One final way to measure the size of Venus is to consider its mass. It has a mass of 4.868 x 1024 kg., just over 81% of Earth’s. These physical characteristics have led many scientists to call Venus the sister planet of Earth.
Size characteristics are the only things that Earth and Venus have in common. At 462°C, Venus has an average temperature that is 410°C higher than the hottest deserts on Earth. The temperature on the Venusian surface can melt lead. You have to be 50 km from the surface to find temperatures that are anything like here on Earth.
Temperature is not the only extreme on Venus. The atmosphere would prevent any life as we know from surviving. To start with, the atmospheric pressure is 92 times that of Earth. It is choked with volcanic ash, sulfuric acid clouds, and is made of 95% carbon dioxide. There are constant hurricane force winds churning the atmosphere. Sustained winds in excess of 360 kph are always present. The conditions on the planet are so extreme that probes can only last a few hours.
The surface shows over 1000 volcanoes or volcanic remnants that are over 20 km in diameter. There are no small impact crater, because the atmosphere is too thick to allow small objects to penetrate to the surface. Scientists believe that the entire surface of the planet was been replaced by volcanic activity 300 to 500 million years ago.
Venus has been visited by spacecraft several times. NASA sent Mariner 2 in 1962. It was the first spacecraft to send information from another planet. The Soviet space program landed Venera 7 in 1970. It was the first spacecraft to land on another planet. NASA’s Magellan mapped 98% of the surface in the early 1990s and the European Space Agency currently has the Venus Express in orbit studying the planet’s atmosphere. In all, we have gained a great deal of information about this inhospitable planet in the last 30 years.
We have also recorded a whole episode of Astronomy Cast that’s just about planet Venus. Listen to it here, Episode 50: Venus.