Out of all the planets in the solar system, Venus might be the one that closely resembles poet Dante Alighieri's seventh ring of hell. The second planet from the sun, Venus is covered with mountains and scorching lava plains. This slightly smaller 'sister' planet of Earth is covered in a weighty atmosphere mostly made of carbon dioxide, with clouds of sulfuric acid.
However, a new research argues that the planet may have once been characterized by temperate conditions and liquid water capable of supporting life, until a dramatic transformation more than 700 million years ago restructured the planet's atmosphere.
The study presented last week at the EPSC-DPS (European Planetary Science Congress and Division for Planetary Sciences in the American Astronomical Society) joint meeting builds on previous research from NASA's Pioneer Venus Project that suggested Venus might have once had shallow oceans of water.
"Our hypothesis is that Venus may have had a stable climate for billions of years," said Michael Way, from The Goddard Institute for Space Studies.
The scientists ran five simulations assuming different levels of water coverage across Venus. In three out of five simulations, it was assumed that Venus had a topography similar to what we see today but with an ocean averaging 310 meters (1,017 feet), a shallow layer of water averaging 10 meters (33 feet), and a small amount of water that was locked in soil. They then compared those against a scenario accounting for a planet with Earth's topography and oceans reaching 158 meters (518 feet) deep.
Researchers then simulated environmental conditions at 4.2 billion years ago, 715 million years ago, and today by adapting a 3D general circulation model to account for an increase in solar radiation seen in our Sun over time and changing atmospheric compositions over Venus.
Their result says, Venus would have been able to maintain stable temperatures between 20 and 50°C (68 and 122°F) for about 3 billion years. Over the next 3 billion years, the planet may have evolved like Earth and locked CO2 into silicate rocks in the planet's surface. These conditions may have been maintained up until today if a mysterious cataclysmic event had not occurred.
Between 700 and 750 million years ago, a series of events released or "outgassed" carbon dioxide stored in the planet's rocks. Scientists believe that it was likely linked to volcanic activity, leading to a greenhouse effect that led to the hellish conditions in Venus today.