Interior of Venus

Here’s a mystery wrapped in an enigma: what is the interior of Venus? Here’s the problem. The surface of Venus is shrouded by thick clouds of carbon dioxide that obscure any telescope’s view of the planet. Furthermore, this thick, hot atmosphere raises the temperature of Venus to the point that it’s hot enough to melt lead. Any spacecraft that landed on its surface have been destroyed within a few hours. So imagine how difficult it is to study the interior of Venus.

The reality is that scientists don’t have any direct evidence about the interior of Venus. All they can do is make assumptions, but there are a few clues to go on. For starters, the density of Venus is very similar to the density of Earth. This means that the interior of Venus is probably similar to the density of Earth. This would mean that the planet has a solid or liquid core of metal about 3,000 km thick. This is surrounded by a mantle of rock 3,000 km thick. And the outer crust is about 50 km thick.

When spacecraft finally reached Venus, they were equipped with radar instruments that allowed them to peer down through the thick clouds and map out the surface of the planet. They found impact craters and a large number of volcanoes, but one of the interesting things was that the surface of Venus is actually pretty young. It’s believed that some kind of dramatic event about 300-500 million years ago completely resurfaced the planet, erasing all of its old impact craters and evidence of volcanism.

Scientists have another hint at the interior of Venus. This comes from the fact that Venus doesn’t have a planetary-wide magnetic field like the Earth. Our magnetic field is believed to come from the convection of metal at the Earth’s core due to temperature differences between the inner and outer core.

When this resurfacing event happened hundreds of millions of years ago, it shut down plate tectonics on Venus. And without plate tectonics, the heat from within the planet wasn’t able to easily escape. The interior of the planet would have remained to hot to allow convection to happen in the interior of Venus. So the lack of a planetary magnetic field does tell scientists that there’s something interesting about the interior of Venus.

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 Hubblesite’s News Releases about 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.

References:
NASA Solar System Exploration: Terrestrial Planets
Venus Interior