As recently as the mid-20th century, science fiction writers envisioned Venus as a watery world inhabited by exotic humanoids. This fantasy was partially based on what astronomers knew about the planet at the time. Through telescope observations, researchers could see that a dense atmosphere veiled Venus.
Obscured by clouds, sci-fi writers envisioned the planet as an Amazon-like water world. A shrouded surface only fueled their imaginations about Venus’ inhabitants. However, a new study suggests that, as is sometimes the case, the sci-fi writers were right—sort of. The research posits that millions of years ago Venus had a temperate climate and possibly liquid water on its surface, Digital Trends reports.
When humanity finally sent spacecraft to Venus in the 1960s, all notions of Earth’s sister planet as a watery paradise went out the window. Researchers discovered that the opposite was true. Venus revealed itself as a sulphuric acid-drenched desert hellscape with temperatures upwards of 900 degrees Fahrenheit. Still, that may not have always been the case.
Water World to ‘Hellish Hot-House’
The Goddard Institute for Space Science’s Michael Way presented the new findings at the 2019 EPSC-DPS joint meeting. “Our hypothesis is that Venus may have had a stable climate for billions of years,” Way said in a statement. “It is possible that the near-global resurfacing event is responsible for its transformation from an Earth-like climate to the hellish hot-house we see today.”
The team used five different computer models. Each one assumed different amounts of water coverage on the planet’s surface. All five simulations indicated that Venus could maintain a liquid water-friendly climate between 122 degrees at the hottest and 68 degrees on the cooler side. As such, thoughts about lifeforms on Venus could have proven true if not for the outgassing of carbon dioxide.
Through their models, the team predicted the state of Venus between 4.2 billion and 715 million years ago. Soon after its formation, Venus began to cool and its atmosphere would have largely consisted of carbon dioxide. Assuming that Venus developed similarly to Earth, Venus’ silicate rocks would have soaked up much of the greenhouse gas.
By 715 million years ago, the team posits, Venus would have had a stable climate. Moreover, it may have had a nitrogen dominated atmosphere much like Earth’s. Soon after though, a massive outgassing event released much of the carbon dioxide stored in the rocks. This would have triggered a runaway greenhouse effect, heating the planet to its Hadean temperatures today.
But exactly what caused the outgassing remains a mystery. Way and his team suggest that it had something to do with the planet’s volcanic activity. “Something happened on Venus where a huge amount of gas was released into the atmosphere and couldn’t be re-absorbed by the rocks,” Way said. “On Earth we have some examples of large-scale outgassing, for instance, the creation of the Siberian Traps 500 million years ago which is linked to a mass extinction, but nothing on this scale. It completely transformed Venus.”
Life On Venus?
The ultimate question remaining is: Could Venus have supported life?
According to Way, “We need more missions to study Venus and get a more detailed understanding of its history and evolution.”
“However, our models show that there is a real possibility that Venus could have been habitable and radically different from the Venus we see today. This opens up all kinds of implications for exoplanets found in what is called the ‘Venus Zone’, which may in fact host liquid water and temperate climates.”