Venus might be a habitable planet today — if it wasn’t for Jupiter

RIVERSIDE, Calif. — From active volcanoes to possible life in the planet’s clouds, Venus continues to be a newsmaker in 2020. Now, a new study finds the second planet might still be habitable today if it wasn’t for one of its neighbors. Researchers say Jupiter has radically changed Venus’ orbit, turning it into a scorching wasteland over the centuries.

A team led by the University of California, Riverside believes Jupiter was once much closer to the sun. As the massive planet moved further away, about a billion years ago, it affected the orbit of other planets in the solar system. For Venus, this shift likely caused most of the water to evaporate and any possible life as we know it to die off.

“One of the interesting things about the Venus of today is that its orbit is almost perfectly circular,” says UCR astrobiologist Stephen Kane in a university release. “With this project, I wanted to explore whether the orbit has always been circular and if not, what are the implications of that?”

Animation depicts eccentricities of the inner planet orbits, and illustrates how circular the orbit of Venus is. (ChongChong He / UCR)

Jupiter’s disruptive move

Jupiter, the solar system’s fifth planet, is a literal gas giant. The planet is two-and-a-half times more massive than all the other planets combined. Its size gives it so much gravitational pull, it can disturb distant objects much like the sun.

The study reveals that while Jupiter was forming, it actually moved closer to the sun as it interacted with disc of gas and dust which helped to form all the planets. Once Jupiter began moving further out into space, it likely made Venus uninhabitable.

Kane and the team use a model of the solar system to calculate how drastic this change is. This model creates a scale of 0 to 1, with zero being a perfectly circular orbit and one meaning a planet doesn’t even finish one trip around a star.

Today, Venus has an orbit of 0.006, the most circular path of any planet in our solar system. A billion years ago however, the model reveals Venus had an orbit of about 0.3. Researchers say this shape gives the planet a much higher chance of supporting life. That life however, would not have survived this seismic shift.

“As Jupiter migrated, Venus would have gone through dramatic changes in climate, heating up then cooling off and increasingly losing its water into the atmosphere,” Kane explains.

Did a once-habitable Venus leave a clue behind?

Composite of images taken by Japanese spacecraft Akatsuki of Venus. (Image credit: JAXA / ISAS / DARTS / Damia Bouic)

Scientists believe a recent find in the fiery and toxic environment may prove there was once life on Venus long ago. Kane points to the discovery of phosphine in the planet’s clouds, a rare molecule usually produced by living microbes.

The astrobiologist suggests these particles may very well be “the last surviving species on a planet that went through a dramatic change in its environment.”

There is a problem with this theory. Currently, Venus is incredibly inhospitable on the ground and in the sky. With ground temperatures near 800 degrees Fahrenheit and clouds that are 90 percent sulfuric acid, it’s hard to think any amount of life could survive here for a billion years. Although Kane says it’s difficult to live without liquid water for that long, it’s not impossible.

“There are probably a lot of other processes that could produce the gas that haven’t yet been explored.”

The researchers say understanding what happened on Venus, and why the conditions are no longer livable, can help explain climates shifts on Earth.

The study appears in the Planetary Science Journal.

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