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Venus is now a hell desert, perhaps because Jupiter pushed it around

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Oct 7, 2020, 8:54 PM EDT (Updated)

If there is a hell in the solar system, it is Venus, which is choked by clouds of sulfuric acid and an average surface temperature that can melt lead. But could the conditions that gave this infernal planet its reputation have been another planet’s fault?

Blame Jupiter. At least a research team from UC Riverside now is. After running simulations that showed how the gas giant (which is two and a half times the mass of all the other planets in the solar system combined) formed, they determined it had been able to shove what might have once been a habitable planet into an orbit that made it inhospitable. Jupiter’s gravity is intense enough to instantly flatten a human. Something with that much power can push around smaller planets as it moves around, which is what it probably did to Venus about a billion years ago.

Planets don’t usually meander around unless they happen to be rogue planets. Those that are orbiting stars tend stay in those orbits indefinitely unless some outside force interacts with them. Sometimes an intruding object can throw an otherwise stable planet off, especially if it has the size and might of Jupiter. This phenomenon has been observed many times in other planetary systems.

“Jupiter is by far the most massive planet in our solar system and so has had a major influence over the orbits of the other planets,” UC Riverside planetary scientist Stephen Kane, who led a study recently published in The Planetary Science Journal, told SYFY WIRE. This enormous gravitational influence of Jupiter combined with its migration means that it played a major role in the final architecture of our solar system. “

Kane and his team wanted to see what Venus’ orbit was like before Jupiter supposedly pushed it around, and whether its original orbit could have been habitable. Venus has a nearly circular orbit with very low eccentricity today. The eccentricity of a planet’s orbit can range between zero, which is a perfect circle, and 1, which would mean the planet wouldn’t even be able to complete an orbit around its star and end up jetting off into space before it ever did. While the orbit of Venus has an eccentricity of 0.006 today, computer simulations found that its eccentricity was once 0.31 — meaning there was a much higher chance of it being a place where life could thrive instead of burn.

Could anything have ever lived here? Credit: NASA

Jupiter was probably also responsible for upping the eccentricity of Venus’ orbit back then. Therefore, it might have been Jupiter that made Venus habitable before its far-reaching gravity affected tidal forces that forced the smaller planet into a more circular orbit. Cosmic objects that get too close to one another can distort each other’s tidal forces. Tidal dissipation, or the loss of tidal energy, can occur as a result. This is what causes the Moon to back off of Earth. Venus does not experience enough tidal dissipation to move around much today, but Kane’s team believes that what is no longer there could mean there was once water on its parched landscape.

“We used a code that simulated orbital dynamics,” Kane said. “That means we used the locations of the planets of the solar system and calculate their gravitational effect on each other. The code then moves the planets in their orbits and repeats the calculations. This process was repeated many many times to calculate any changes in the orbits. I then changed the location of Jupiter and repeated all of the calculations again to show how the location of Jupiter effects the orbit of Venus.”

There might have even been as much water as Earth. Venus could have had surface oceans or at least subsurface oceans in the deep past, though we don’t have enough evidence to tell us if and where those oceans existed (if they existed at all). It is possible that Venus and Earth had similar amounts of water, and it was those primordial oceans that created tidal dissipation from about 3 billion years to 1 billion ago. Kane believes the ratio of deuterium to hydrogen in what is now the toxic fog in what is now the atmosphere of Venus is evidence of immense water loss. The presence of water could have also meant life.

If the phosphine recently discovered in the Venusian atmosphere could have been produced by hypothetical alien microbes hiding somewhere in those acidic clouds right now, it could mean these microbes are the last surviving organisms on the planet.

“Right now, no one is completely sure what the source of the phosphine detected in the Venus clouds is,” Kane said. “The possibility of life in the clouds extends the prospects of a previous temperate surface environment for Venus to the present epoch. In other words, biology in the atmosphere could be the last surviving members of a prior Venusian biosphere. If confirmed as being the result of life in the clouds, this result would be an extraordinary lesson in how life really can adapt to all available niches within an environment.”

If NASA is seriously considering sending humans to Venus, there must be a way to get out alive.

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