Venus is a tricky place to study because it’s shrouded in a thick atmosphere that hides its surface. And if you can’t even see its surface, imagine how difficult it must be to study the interior of Venus. But scientists have been making steady progress towards understanding the interior of the planet, and learn about the core of Venus.
Here on Earth, scientists study the core of the planet by measuring how seismic waves move through the planet after earthquakes. As they pass through the different layers of the Earth’s interior; the core, the mantle, and the crust, the waves reflect or bend depending on the change of density that they’re passing through. Well, the surface of Venus is hot enough to melt lead, and spacecraft are destroyed within a few hours of reaching the surface of Venus, so no readings have been gathered about Venus’ core directly.
Instead, scientists assume that the core of Venus exists based on calculations of its density. The density of Venus is only a little less than the density of Earth. This means that Venus probably has a core of metal about 3,000 km across, surrounded by a 3,000 km thick mantle and a 50 km thick crust.
Scientists aren’t sure if the core of Venus is solid or liquid, but they have a few hints. That’s because Venus doesn’t have a planet wide magnetic field like the Earth. It’s believed that the Earth’s magnetic field is generated by the convection of liquid in the Earth’s core. Since Venus doesn’t have a planetary magnetic field, it’s possible that Venus’ core is made of solid metal, or maybe there isn’t enough of a temperature gradient between the inner and outer core to made this convection happen.
It’s believed that a global resurfacing event that occurred about 300-500 million years ago might have something to do with this. The entire surface of Venus was resurfaced, shutting down plate tectonics. This might have led to a reduced heat flux through the crust, trapping the heat inside the planet. Without the big heat difference, there’s little heat convection, and so no magnetic field coming from the core 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.
We have recorded a whole episode of Astronomy Cast that’s only about planet Venus. Listen to it here, Episode 50: Venus.