Venus May Have Once Been Habitable, New Climate Study Says

New climate models suggest that Venus was once habitable.

Scientists have long hypothesized about Venus' capability to support life. But studies about Venus have been resurfacing, including recent climate models developed by NASA's Goddard Institute for Space Studies and other research groups, and they are offering more evidence that the planet may have once been habitable and have remained so for many years.

"If Venus was spinning more rapidly, all bets are off," Michael Way from NASA's Goddard Institute for Space Studies and lead author of the study, told Gizmodo.

"[Under right conditions] you get temperatures almost like Earth. That's remarkable."

The scientists used 3-D computer modeling based on topographic data gathered by the Magellan spacecraft to simulate how Venus may have evolved if it began as a living planet like Earth. They found that despite the fact that Venus would have been more exposed to the Sun's radiation than the modern Earth 2.9 billion years ago, the new models predicted that the planet had an average surface temperature of only 11 degrees Celsius (52 degrees Fahrenheit).

Researchers also found that by approximately 715 million years ago, Venus's surface may have only warmed up by four degrees, which suggested that the planet's temperature remained within the habitable range for at least 2 billion years.

However, the findings are based on the assumption that ancient Venus had the same topographical and orbital characteristics as today's Venus. But when the researchers reran their models to make ancient Venus look like Earth, the surface temperatures increased.

Moreover, the researchers also found that after speeding up the rotation of Venus to match a 16-Earth day period, the planet's temperatures rose again.

According to the scientists, one of the most notable characteristics of Venus is its high-altitude wind speeds, which is 60-times faster than the planet's rotation. In a hypothetically younger Venus with a slower rotation, the climate model predicted that layers of cloud would have shielded the young planet from the increased level of solar radiation. But when Venus rotates quickly, the cloud cover doesn't form.

"Earth has many [circulation] cells because our planet rotates fast," Way said. "But if you rotate slowly, you have one in the north and one in the south, period. That changes the atmospheric dynamics of the world by a significant amount."

According to the researchers, the discovery could have important implications for exoplanetary studies of the habitable zone.

The new study will be published in the journal Geophysical Research Letters.