Did Life Exist on Venus Before Earth? | Unveiled

Did Life Exist on Venus Before Earth?

Earth’s evil twin is about the same size and mass, but it has an incredibly toxic atmosphere full of heavy CO2, scorching temperatures, and acid rain. Venus is so inhospitable that we gave up on sending probes out there before the turn of the century. However, plenty of evidence suggests that it wasn’t always this way.

This is Unveiled, and today we’re answering the extraordinary question; did life exist on Venus before Earth?

The surface of Venus is hostile to life as we know it. Its atmosphere is made up largely of 96.5% carbon dioxide, and is so thick and heavy that the atmospheric pressure at its surface is 92 times stronger than Earth’s. That means that walking on Venus would be like walking on the seafloor 3,000 feet down - through an ocean made of sulfuric acid at temperatures exceeding 880 degrees Fahrenheit. Every other planet in our solar system is inhospitable to us without some significant tweaking. However, Venus’s rotation also sets it apart. Like Uranus, it rotates in the opposite direction to the other planets in the solar system. Its rotation is also extremely slow; a day/night cycle on Venus takes 116.75 Earth days. At least Venus’s gravity is something we don’t have to worry about; its gravity is 8.87m/s2, only slightly less than Earth’s.

While today its size and gravitational pull are the only things similar to our own planet, scientists have used these similarities to suggest that once upon a time, Venus was capable of supporting life. A NASA study showed that in computer models that assumed various levels of water coverage, Venus could have sustained liquid oceans for 2-3 billion years of its 4.5-billion-year lifespan. Considering Mars only had liquid water for 400 million years, Venus is a much likelier candidate for hosting alien life. In these simulations, it was found that temperatures on Venus ranged between a relatively comfortable 68 to 122 degrees Fahrenheit. That’s about the same temperature as parts of Earth close to the equator, where humans have been living for thousands of years. So it’s definitely possible for life, including intelligent life, to develop in these conditions.

This revelation has led to a change in our understanding of what kind of planets may be habitable outside of our solar system. Previously, the “Venus Zone” was thought to be a region of space where there was simply too much solar radiation to maintain liquid water. But now we have many reasons to believe that this isn’t true. This means that lots of exoplanets we’ve discovered and written off as being outside of what we consider to be the “Goldilocks Zone” might harbour extraterrestrial life after all. This not only increases our chances of discovering alien life, but also of one day finding a second home for humanity if we need to. These “Venus Zone” planets might be a little warmer than we’re used to, but if they can sustain a decent amount of liquid water for billions of years then they’re definitely worth our time.

But if Venus might have once been capable of supporting life, what made it the toxic wasteland it is today? Scientists don’t have a solid answer for this. One popular theory is that Venus experienced an “outgassing”, a volcanic event that led to a huge outpouring of poisonous gases, like CO2, and a runaway greenhouse effect around 715 million years ago. Venus has active volcanoes to this day. The dense atmosphere and high volume of CO2 could be evidence of an apocalyptic period of Venusian warming. With climate change one of the most pressing issues facing mankind, understanding how Venus came to be this way could help us prevent the same thing from happening to Earth. If they were identical twins once, they could become identical twins again . . . and NOT by way of Venus’s clouds dissipating and allowing alien life to thrive.

Then again, other theories say that Venus’s liquid ocean may have also been its downfall. Unlike Earth, Venus doesn’t have any moons, but if it once had water, it would still have had a “solar tide” controlled by the sun’s gravity. Some evidence suggests that tides can actually slow the rotation of a planet down. In 2019, researchers at Bangor University in Wales argued that this may have occurred on Venus, causing its incredibly slow rotation, and resulting in the planet becoming uninhabitable. One barrier to further study is the fact that Venus’s surface is only 500 million years old, so it formed after the planet was already hostile to life.

While Venus’s clouds might be full of sulfuric acid, the space above the clouds has often been suggested as the site of a potential human colony. About 30 miles over the planet’s surface, the pressure is similar to Earth’s at sea level, and the temperature drops to 140 degrees Fahrenheit. Besides being friendlier to humans though, these clouds could be the last refuge of any life that may have existed on the planet. Sturdy, microbial creatures could be living in those clouds quite happily. We know that some organisms can thrive in extreme conditions on Earth. Tardigrades, for example, can survive in temperatures ranging from minus 328 degrees Fahrenheit to 300 degrees Fahrenheit, and our own clouds are home to all kinds of microbial lifeforms. So clouds, thin and light as they may be, are ecosystems all of their own, and Venus’s might be just the same.

It’s also possible that such organisms could have spread to Venus from Earth. Rocks ejected by Earth, by violent impacts, for instance, could have reached Venus before, just as Venusian materials could have reached our own modest shores. This means that an interplanetary migration of small organisms could have taken place in the past, and that humans are naturally Venusian in origin - or that Venusian lifeforms are descended from Earth! It’s equally possible that both planets had life seeded on them from another body in the solar system, and that these lifeforms evolved completely separately on neighbouring planets for billions of years before Venus was devastated by greenhouse gasses. We won’t know for sure until we study Venus further, but it’s definitely possible that our microscopic ancestors came from another world.

In the wake of revelations about Venus’ past, interest in our twin planet has grown. While NASA hasn’t sent a probe to Venus since 1994, they and other space agencies are planning to change this. In the 2020s and beyond, there’ll likely be several missions to explore Venus. NASA is considering two mission proposals, one named VERITAS that would use radar to map Venus’ topography, and another called DAVINCI that would send a probe to study the composition of the planet’s atmosphere. The European Space Agency and Indian Space Research Organization are making plans to launch orbiters, and Roscosmos is looking into an orbiter, lander, and research station to analyze Venus’ surface, volcanoes, and weather conditions. While we don’t have plans to try and send humans to Venus any time soon, we’ll definitely learn more about what makes this strange planet tick across the next few years.

We don’t know for sure whether life once existed on Venus, but we do know that it could well have had liquid oceans and been habitable for billions of years. And that’s whether or not life existed on Venus before Earth.