Venus is known for its incredibly dense atmosphere, devastating pressures, and surface temperatures hot enough to melt lead. In other words, this world has some of the least comfortable conditions in the entire solar system. However, everything is not so simple on Venus because it is located in a habitable zone and therefore could potentially be a suitable candidate for habitation.

It will take a lot of time and technology to make Venus habitable, which humanity does not yet have. However, the fact that a planet like Venus is in a habitable zone does not automatically mean that such a world would be suitable for the formation of life.

This is because the current definition of a habitable zone only considers the amount of sunlight reaching the planet. If it is too much or too little, there can be no liquid water on the surface and therefore the planet is not a good candidate for life.

Venus photographed by NASA Parker Solar Probe

By this simple criterion Venus seems fit for life; that is, it could potentially support water. But that’s not the case.

As it turns out, there are many Venus-like planets in the habitable zones, and the scientific community may need to change their approach to the definition of “habitable zone”.

what happened to venus

Astronomers aren’t entirely sure what happened to Venus. Without detailed measurements of the surface, we can only guess at how this planet became so disturbing.

Because Venus is roughly the same size as Earth and formed in approximately the same region, many planetologists believe Venus is very similar to Earth and has almost the same number of key components: carbon, oxygen, silicon, and water. Venus is likely to be covered with pools and even oceans of liquid water. But then something went wrong…

It is possible that a long period of active volcanism triggered processes on Venus, which led to what is happening to this planet today. Perhaps it was the normal evolution of the sun when its increased light evaporated all the water on the surface. Or maybe it was a process we don’t yet understand.

The surface of Venus in the artist’s imagination / Photo by Shutterstock

Whatever the precise mechanism, Venus suffered from a large-scale greenhouse effect. As the atmospheric pressure increased, the temperature increased, causing more gas to be released into the air, feeding off each other in a catastrophic cycle.

As soon as enough gas entered the atmosphere, Venus could not cool down and would absorb almost all of the radiation from the Sun. As a result, the oceans dried up and all the water entered the atmosphere and eventually leaked into space never to return. If there was any life in these primitive oceans, it didn’t have enough time to evolve.

Search for habitable worlds

In the search for habitable worlds, the first step is to identify planets in their respective regions of their stars, as this is where the Earth is in its orbit around the Sun, and Earth is the only known place in the universe. where we can definitely say life is.

But planets are complex, so it is very difficult to give a simple definition of a populated area. For example, Venus must have water on its surface; receives exactly as much sunlight as it needs. But with the planet’s super-dense atmosphere, the temperature is too high to support any liquid.

Now a group of researchers has tried to find a dividing line between Earth-like planets and Venus-like planets. In a recent paper in the ArXiv preprint database, they used a relatively simple model of planetary atmosphere and the type of radiation these planets would receive from different stars.

There are many Venus-like planets in the universe / Photo by Guillermo Ferla

For each setup with different types of stars and different orbits around those stars, the researchers started with a terrestrial mixture of atmospheric gases (mostly nitrogen with a small amount of carbon dioxide) and gradually increased the amount of carbon dioxide to mimic the onset of massive stars. – scale greenhouse effects. They then allowed the models to evolve to see what would happen to the composition of the atmosphere over time.

Thanks to this model, scientists were able to determine where and under what conditions “Venus-like” planets are, and where Earth-like planets are, which can maintain conditions for the beginning and continuation of life.

Everything is much more complicated

The researchers discovered that Venus-like worlds are surprisingly common, with large areas of the population potentially closed to life.

For example, around the sun-shaped star, the traditional enclave covers 95% to 167% of the Earth’s orbital radius. But these models have shown that the outer edge of the “belt of Venus” reaches 135% of Earth’s orbit, meaning that one day our planet could suffer from the same large-scale greenhouse effect.

F-type stars weighing 1.0-1.4 times the mass of the Sun performed best: about 40% of their inhabited areas survived. Small red dwarfs had the worst, as they produced most of their radiation in the infrared, which was easily blocked by atmospheric gases. For these stars, the Venus region has absorbed everything but the outer edges of the inhabited region.

However, one should not lose hope. These models are simple and planets are complex. Not every planet that can be affected by the large-scale greenhouse effect will necessarily suffer from it. Atmospheric mixing, shielding from planetary magnetic fields, additional water, or plate tectonics can alter the planets’ orbits. Not every Venus-like planet is destined to be a hellish world, but we should take a closer look at worlds where life can exist.