Evrim Yazgin
Cosmos science journalist
A new paper argues that the search for life outside our planet could be aided by looking in an unexpected place: the extremely hot, toxic planet Venus.
Venus is uninhabitable. It’s like our planet’s evil twin, with a diameter only 5% smaller than Earth’s.
But the average surface temperature on Venus is 464°C – high enough to melt lead. Its surface is dotted with lava-spewing volcanoes. It’s “runaway greenhouse effect” is caused by a toxic atmosphere of carbon dioxide with clouds of sulfuric acid. Atmospheric pressure on the planet’s surface is 90 times higher than sea level on Earth – it’s the equivalent of been a kilometre under water.
So, how can this hostile planet help scientists find extraterrestrial life, which is what is argued in a paper published in Nature Astronomy.
“We often assume that Earth is the model of habitability, but if you consider this planet in isolation, we don’t know where the boundaries and limitations are,” says first author Stephen Kane, a University of California, Riverside astrophysicist. “Venus gives us that.”
Kane says that studying Venus could help in the search for alien life precisely because Venus and Earth are so alike yet turned out so different.
“If you consider the solar energy received by Earth as 100%, Venus collects 191%. A lot of people think that’s why Venus turned out differently,” Kane says. There is, however, more to this picture according to Kane.
“But hold on a second. Venus doesn’t have a moon, which is what gives Earth things like ocean tides and influences the amount of water here.” Venus also doesn’t have a magnetic field, probably due to its smaller core, which on Earth was vital in allowing the first organisms to survive by deflecting harmful cosmic radiation.
Kane hopes that NASA missions DAVINCI and VERITAS – scheduled to launch by the end of the decade – will help build a fuller picture of Venus.
“DAVINCI will measure the atmosphere all the way from the top to the bottom. That will really help us build new climate models and predict these kinds of atmospheres elsewhere, including on Earth, as we keep increasing the amount of CO2,” Kane explains.
The missions will also map the surface of the planet, giving information about how it has changed over time.
As a clearly inhospitable world, Kane says that studying Venus could help astronomers determine whether or not exoplanets light-years away are habitable or not.
But there is another, more sobering advantage to studying Venus’s hostile environment.
“One of the main reasons to study Venus is because of our sacred duties as caretakers of this planet, to preserve its future. My hope is that through studying the processes that produced present-day Venus, especially if Venus had a more temperate past that’s now devastated, there are lessons there for us. It can happen to us. It’s a question of how and when,” Kane says.
