Had Venus drawn slightly luckier tickets in the cosmic lottery, our solar system could host two habitable planets today, according to recent simulations from a group of NASA researchers. Instead, our neighbor is a desolate place—and might give us a terrifying glimpse of our own future.
Planetary scientists have traditionally viewed Venus’s hellish temperatures, carbon dioxide-saturated atmosphere, and congealed crust as the inevitable outcome of its place in the solar system. Sitting too close to the sun, the hapless planet was doomed from birth to be burnt to a crisp. In recent years, however, an alternative possibility has thrown some shade at this simple story. Given the right starting conditions, cloud cover could have protected Venus from the barrage of sunlight and kept it balmy and wet for billions of years, according to simulations presented this week at a planetary science conference in Switzerland. In this scenario, Venus may have actually been the solar system’s first habitable planet… until some unknown catastrophe smothered it in carbon dioxide.
Venus failed to maintain this cycle, so today its atmosphere overflows with carbon dioxide. The question is why. According to the traditional story, a warming sun quickly evaporated the young planet’s oceans into the sky, where they formed a dense, stick atmosphere that trapped incoming heat with deadly efficiency. Eventually, the surface grew as hot as the interior, which put a stop to the earthquakes and other tectonic activity that had previously helped Venus let off steam. Without tectonic mixing, says Anthony Del Genio, a researcher at the NASA Goddard Institute for Space Studies and co-author of the recent research, the crust became like “a rigid lid that just builds up heat and pressure on the inside until the whole planet blows.”
Heating from the evaporated oceans made Venus blow it’s top just a few hundred million years ago, according to observations of its young and unblemished surface. Volcanoes erupted across the planet, flooding the atmosphere with carbon dioxide, which in turn made the planet the lifeless rock we see today.