Is Venus the Hottest Planet?

Which is the hottest planet in the Solar System? Is it Mercury, which orbits closest to the Sun? Maybe it’s the Earth, with its warm oceans and tropical temperatures. Nope, Venus is the hottest planet in the Solar System, with an average surface temperature of 461.85 °C.

So why is Venus the hottest planet? It all comes down to atmosphere, and distance from the Sun. Mercury orbits closer to the Sun, but it has no significant atmosphere to trap the heat it receives from the Sun. On the day side of Mercury, temperatures soar to 425 °C. But then on the night side, the temperatures dip down to -190 °C. That’s only about 80 degrees above absolute zero.

Even though we’re much further away from the Sun than Mercury, our atmosphere traps the Sun’s heat and keeps us warm. Temperatures on Earth never dip down as low as Mercury’s lowest temperatures; not even close.

Venus, on the other hand, has an incredibly thick atmosphere. The atmospheric pressure on the surface of Venus is 93 times greater than what we experience on the surface of Earth. You’d have to swim down to 1 km beneath the surface of the ocean to experience that kind of pressure. Furthermore, the atmosphere of Venus is made up almost entirely of carbon dioxide, which we know is a greenhouse gas, that helps trap heat better.

Visible light filters through the cloud tops on Venus, but then it’s trapped as it tries to reflect back into space. Over time, the constant heating from the Sun has increased the temperatures on Venus to the current point, where they’re the hottest in the Solar System.

And that’s why Venus is the hottest planet in the Solar System.

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 a link to NASA’s Solar System Exploration Guide on Venus.

We have recorded a whole episode of Astronomy Cast that’s only about planet Venus. Listen to it here, Episode 50: Venus.