![]() ![]() When looking at a planet’s past, Kiefer said, we need to understand how the planet operates as a whole: “We’ve got to think of Venus as a system. However, Kiefer said, it is also possible that there was a tectonic event that occurred first and caused the altered climate: “It’s a chicken and egg question.” Those known losses will change the tectonics,” explained Venus tectonics expert Walter Kiefer of the Lunar And Planetary Institute. With less tectonic activity, it could be harder for the planet to recycle water, making it less hospitable to potential life. And active tectonics, like we have on Earth, is thought to be important for habitability as it stabilizes the climate. With the planet’s surface heating faster than its interior, there’s less movement of material within the planet. ![]() Changes to the atmosphere also affect the planet’s tectonics. These changes didn’t only affect the planet’s atmosphere though. An artist’s depiction of a young planet Venus That’s thought to be how Venus became the hellish place it is today. Greenhouse gases built up in the atmosphere, raising the temperatures even higher. The higher temperatures caused the surface water to evaporate, forming water vapor in the atmosphere, which was split by sunlight into oxygen and hydrogen, which was then lost into space. At some point, Earth and Venus diverged sharply and Venus entered what is called a runaway greenhouse phase. Whether or not there was water there, however, scientists agree that Venus didn’t stay comfortable. A study by NASA planetary scientists in 2016, for example, simulated historical climate conditions on Venus and found that if oceans were present, the planet could have maintained stable temperatures of between 20 and 50 degrees Celsius for around three billion years.īut these models required that water already existed on the planet, and it’s debatable whether that was the case. So it’s possible, though disputed, that Venus could have had water oceans in its distant past. There are some differences - Venus is closer to the sun and therefore receives more heat, and it is less dense than Earth, and it rotates more slowly - but overall, the two planets could have followed a very similar path in their early years. They are also both within a boundary in the solar system called the snow line, which is the point at which water forms ice grains. ![]() The two planets are of similar size, and they formed from similar materials in the earliest stage of the solar system. A tale of two planetsĪs different as the two planets are today, Venus and Earth were once very similar. To find out what it would take for our other neighboring planet to have been habitable and why it isn’t anymore, we spoke to two Venus experts about what we know about Venus’s history - and what we don’t know yet but might soon learn. One of James Webb’s first targets is Jupiter. Perseverance rover finds conditions where life could have thrived on Mars The art and science of aerobraking: The key to exploring Venus ![]()
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