Venus had a rather complicated and unfortunate history. Planetary scientists suspect that billions of years ago, Venus was quite similar to the Earth: warm, pleasant and rinse with liquid water. But sometimes in the past it has lost its water and turned into a scorching desert.
According to a recent article, Venus it was doomed from the start, but it may have been hastened on its way to the arid city due to the gravitational influence of none other than the solar system’s great bully: Jupiter.
A wandering giant
The first solar system was a total Wild West: lawless and chaotic. For starters, astronomers now strongly suspect that giant worlds they did not form in their current orbits. We can identify this by modeling and sculpting the orbits in the asteroid belt and the distribution of the icy remnants beyond Neptune̵
However, we don’t have a clear picture of exactly how the migration happened. In some models, Jupiter slowly a few inches closer over hundreds of millions of years, followed by Saturn and the rest. But in other models, Jupiter nearly jumps into the orbit of Mars before returning to its current position.
Either way, a dancing Jupiter wreaked havoc on the inner planets. The mass of that planet is so large – it is 2.5 times more massive than all the other planets combined – that every small shift in its orbit attracts and wipes out everything else in the solar system.
Take, for example, Venus. Venus currently has one of the most perfectly circular orbits in the entire solar system. Its eccentricity (the measure of how elliptical an orbit can become) is only 0.007, which means that at the closest approach Venus is 66.5 million miles (107 million kilometers) from the sun, and at its greatest distance it is … 67.7 million miles (109 million km) from the sun.
But second a recent article appeared in the prepress journal arXiv, if Jupiter had migrated inward closer to the sun, it could have pulled Venus into an extremely elliptical orbit, creating an eccentricity of up to 0.3.
Since Venus no longer has that great eccentricity, something must have happened to circularize its orbit, and the authors of the article suggest it was ocean tides. If Venus had large oceans of liquid water (which we suspect it did, as Venus and Earth are roughly the same size and had similar formation histories), then the tides on the oceans could have provided enough friction to stabilize the orbit. of that planet in a nice constant circle.
But that elongation of the orbit due to Jupiter may have had another catastrophic consequence: it could have accelerated the transformation of Venus from a tropical wetland to a hellish nightmare.
Our solar system: a photographic tour of the planets
A watery Venus
If you are a planet trying to cling to your oceans of liquid water, an eccentric orbit is a real pain in the neck. We already know this from studies of The history of the Earth that variations in our planet’s eccentricity (due, you guessed it, to gravitational changes and tugs from other planets) have triggered ice ages and glaciation events. Indeed, some profound climatic variations are directly linked to changes in our eccentricity.
However, despite the occasional frozen moment, Earth has managed to hold on to its water. Poor Venus, however, suffered a worse fate. If Venus was sent into a highly elliptical orbit due to Jupiter’s presence in the early days of the solar system, it spent part of its year away from the sun (nice and cool) and some times of the year are too close for comfort.
All in all, the researchers calculate, Venus may have suffered more heat exposure than it is healthy. The problem is that the intensity of the radiation increases rapidly even for small inward shifts of the orbital position. The more time Venus spent near the sun, the worse she suffered.
Even worse, the closer Venus was to the sun, the more susceptible it was to bursts of ultraviolet radiation from solar flares, which were especially important when our sun was a young relative.
The combination of increased heat and increased exposure to high-energy radiation set Venus’s hellish spiral in motion.
When Venus lost its oceans, water vapor in the atmosphere trapped the heat. The trapped heat evaporated more water, which put more water into the atmosphere, which trapped more heat, and around it went into a vicious greenhouse cycle. Without fluids to lubricate Venus’ joints, plate tectonics stopped, allowing carbon dioxide to escape into the atmosphere in dramatic excess, blocking its fate.
Eventually, Venus flipped over and cooked herself to death, leaving our neighbor a nightmare world. And it may have been accelerated on that path by wandering and pillaging Jupiter.
Venus is more than a warning for our greenhouse gas emissions. You may have noticed that astronomers are very interested exoplanets – worlds outside the solar system – and if they could be homes for life. Venus sits right on the inner edge of what is called the habitable zone of our sun, the range where the intensity of light is just right to allow liquid water on the surface of the world.
But the surface of Venus is not habitable at all (although it is clouds could be something else), and this could be Jupiter’s fault. When we go to examine the possibility of life on other worlds, the authors of the article conclude, we must pay attention to any giant planets in those systems. They may have performed Jupiter-like stunts, ruining any chance of life that persisted in the inner worlds.
Read more: “Could the migration of Jupiter have accelerated the atmospheric evolution of Venus?“
Paul M. Sutter is an astrophysicist at SUNY Stony Brook and the Flatiron Institute, host of Ask a Spaceman and Space Radio and author of Your Place in the Universe. Sutter contributed this article to Space.com’s Expert Voices: Op-Ed & Insights.
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