For decades, many scientists believed that Venus, our closest neighbor, was once more like Earth before it turned into the scorching planet with clouds of sulfuric acid we know today.
A new study has shattered that belief in a kinder, gentler Venus.
Earth and Venus are nearly identical in size and sit relatively close to one another in space. But the planet has come to be known as Earth’s “evil twin.” Swaddled in clouds of acid, with hell-like temperatures of 500°C, it is nothing like our hospitable planet. But many have believed that it may have once had liquid oceans and maybe even life.
A team from the University of Cambridge has studied the composition of the Venusian atmosphere. It turns out Earth’s sister planet has always been inhospitable to life. Venus’s atmosphere is just too dry to ever have had enough water to form oceans.
There are two current theories about how Venus evolved. Both are based on climate models. The first suggests that Venus was once cool enough to have water oceans, but that a rapid greenhouse effect turned into its current hellscape. The second is that it has been its current temperature since birth, and that liquid water never existed here.
Instead of looking at climate models, the new research studied Venus’s atmosphere.
To keep a stable atmosphere on Venus, its volcanoes need to spew out the gases that are being broken down and removed from its atmosphere. This happens on Earth, because our volcanoes expel huge quantities of watery steam.
Venus is cloudy but dry
By comparison, volcanic eruptions on Venus are only six percent water. Commented the researchers, “These dry eruptions suggest that Venus’s interior…is also dehydrated.”
Though their study strongly suggests that Venus never held Earth-like life, lead author Tereza Constantinou stressed that other forms of life may exist.
“Any potential life in the Venusian atmosphere would have originated and evolved under entirely different conditions, perhaps adapted to survive in sulfuric acid clouds,” she told ScienceAlert.
NASA’s DAVINCI mission intends to complete a series of flybys and send a probe down to ascertain if life does or once existed there. The current launch date is 2030.
The new insight into Venus has repercussions for the search for hospitable planets in our galaxy. Astronomers look for planets within a certain distance of a host star. This is known as the “habitable zone” and is an area where surface temperatures allow liquid water. It now seems that Venus has always been outside the habitable zone. It seems that a planet’s distance from its star is not as simple a measuring tool as we’ve believed.
