Venus could have been habitable, but Jupiter ruined everything

Venus might not have been a stuffy, waterless hell today if Jupiter hadn’t changed its orbit around the Sun, according to a new study from the University of California.

Jupiter’s mass is 2.5 times the mass of all other planets in the solar system combined. Since it is relatively large, it can disrupt the orbits of other planets.

At the beginning of the formation of Jupiter as a planet, it was closer to the Sun, and then moved away from it due to interaction with the disk from which the planets are formed, as well as with other giant planets. This movement influenced Venus.

Observations of other planetary systems have shown that such migrations of giant planets soon after formation may be relatively common. This is one of the results of a new study published in the Planetary Science Journal.

Scientists believe that planets deprived of liquid water are unable to support life as we know it. While Venus may have lost some water early on for other reasons and may have continued to do so, UCR astrobiologist Stephen Kane said that Jupiter’s movement pushed Venus towards its current inhospitable state.

“One of the interesting things about Venus today is that its orbit is almost perfectly circular,” said Kane, who led the study. “In this project I wanted to find out if she was always like this, and if not, what are the consequences of this?”

To answer these questions, Kane created a model that mimics the solar system, calculating the location of all the planets at any given time and how they pull each other in different directions.

Scientists measure how non-circular a planet’s orbit is between 0 (completely circular) and 1 (not at all circular). A number between 0 and 1 is called the orbital eccentricity. An orbit with an eccentricity of 1 cannot even complete a revolution around the star; it will just fly off into space.

Now the value of the orbit of Venus is 0.006, which characterizes the most circular orbit of all the planets of the solar system. Kane’s model shows that when Jupiter was closer to the Sun about a billion years ago, Venus had an eccentricity of 0.3, and there is a much higher likelihood that it was habitable then.

“As Jupiter migrates, Venus would undergo dramatic climate changes, warming and then cooling and losing water in the atmosphere,” Kane said.

Scientists recently discovered gas in the clouds above Venus, which could indicate the presence of life. Phosphine gas is usually produced by microbes, and Kane says that this gas represents “the last surviving species on the planet to undergo drastic changes in the environment.”

But to do this, Kane notes, microbes would have to maintain their presence in the sulfuric acid clouds over Venus for about a billion years since Venus last had liquid water on the surface – a scenario difficult to imagine, but quite possible.

“There are probably many other processes that can produce gas that have not yet been explored,” Kane said.

Ultimately, it’s important to understand what happened to Venus, a planet that was once probably inhabited and now has a surface temperature of around 430 degrees Celsius.

“I focus on the differences between Venus and Earth and what went wrong with Venus so that we can understand how livable the Earth is and what we can do to take the best care of our planet,” Kane said.

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