Venus is not a nice place if you look at it the way people do. It’s a toxic, super-hot hell for a world named after a Roman goddess of love and beauty. But things weren’t always this way.
In a study, scientists make a case for how ancient Venus could have once had oceans of liquid water and life. About 700 million years ago, a mysterious resurfacing event took all of that away.
Michael Way, a planetary scientist at NASA’s Goddard Institute for Space Studies, says, “We think Venus may have had a stable climate for billions of years.”
“It’s possible that the near-global resurfacing event changed its climate from being like Earth’s to being like a hellish hot house.”
The research, which was shown at the EPSC-DPS Joint Meeting 2019 in Geneva, Switzerland, uses two previous studies by Way and his team as well as papers that model virtualized Venus-like planets and topographies.
In the end, the team says, 3D GCM (general circulation model) modeling supports the “optimistic” view that Venus “spent most of its history with liquid water on the surface, plate tectonics, and a stable temperate climate similar to that of Earth.”
This would have been true for at least 4.2 billion years, or until about 700 million years ago. Around that time, something bad happened on Venus, and ever since then, the planet has been very hot, with a toxic “greenhouse effect” atmosphere made mostly of carbon dioxide and nitrogen that traps heat.
This atmospheric composition is a big reason why Venus has such high temperatures and air pressure. But how did Earth’s “sister” planet get to be like this?
Way says that something happened on Venus that caused a huge amount of gas to be released into the air and not be taken back up by the rocks.
“Large-scale outgassing has happened on Earth before, like when the Siberian Traps formed 500 million years ago, which is linked to a mass extinction, but nothing like this. It changed Venus completely.”
We can’t say for sure that there was life on Venus based on the new research, though. Models show that the planet may have been good for life in the past because it could have had liquid water and a forgiving atmosphere.
We don’t know what happened for sure. Researchers say that a carbonate-silicate cycle similar to the one on Earth, in which CO2 is naturally taken out of the air by being absorbed into rocks, was stopped on Venus. This may have been caused by a period of intense volcanic activity, when magma solidified on the planet’s surface, stopping the cycle and stopping the gas from being reabsorbed.
If they’re right, it means that not only could there have been life on Venus in the past, but that planets like Venus, which are usually thought to be habitable because they’re close to the stars that make them, may not be so barren after all.
Way says, “Our models show that there is a real chance that Venus could have been habitable and very different from how it is now.”
“This could mean a lot for exoplanets found in the “Venus Zone,” which may have liquid water and temperate climates.
At the 2019 Joint Meeting of the EPSC and DPS, the results were shown.