Space

Ancient Venus may have looked a whole lot like Earth

Ancient Venus may have looked ...
Artist's impression of ancient Venus
Artist's impression of ancient Venus
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Artist's impression of ancient Venus
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Artist's impression of ancient Venus

According to computer modeling, the planet Venus could have once been habitable, hosting a shallow-water ocean, and surface temperatures hospitable to life. The simulations are based on present-day observations of Venus, paired with data harvested by previous NASA missions that visited the enigmatic planet.

Often referred to as Earth's twin, current-day Venus is anything but. The tortured world's atmosphere, which is believed to be roughly 90 times as thick as that of our own planet, has led to a runaway greenhouse effect, resulting in surface temperatures of 864 ºF (462 ºC).

However, it is possible that, in its ancient past, this hellish world could have sincerely deserved the moniker of Earth's twin. In the 1980s, NASA's Pioneer spacecraft observed clues that a water ocean may once have existed on Venus. Now, a team of scientists from NASA's New York-based Goddard Institute for Space Studies has run computer simulations designed to model Venus' ancient atmosphere, and come up with some surprising results.

The computer model employed for the simulations is similar in nature to those used to forecast the effects of climate change on Earth. For the purpose of the simulations, the researchers had Venus rotate at the same speed that it does today.

Digital Venus was given an atmosphere similar to that of present day Earth, and furnished with topographical features based on data harvested by NASA's Magellan mission that visited the planet in the 1990s. The researchers then filled the low-lying areas of the planet with a shallow ocean, leaving only the highlands exposed.

According to the team, landmasses on ancient Venus would have been much dryer than their Earthly equivalent. This fairly mundane characteristic could have played a vital part in keeping the planet's greenhouse gas problem at bay, as less water vapor would escape from the ground via evaporation.

It was discovered that Venus' slow rotational period of 117 Earth days, in conjunction with the ancient analog of our Sun used in the study, combined to create a hospitable surface temperature only a few degrees cooler than the temperature on present-day Earth.

The slow spin of the planet, which would expose areas of the surface to the glare of the Sun for months at a time, allowed the heat from our star to evaporate enough water to create a kind of cloud shield. This barrier mitigated some of our Sun's heating influence, which, whilst younger and less hot in the simulations than it is today, would still have bathed the planet in 40 percent more sunlight than that received by present-day Earth.

It is estimated that this Earth-like Venus could have remained habitable in this way for around 2 billion years.

However, eventually, the sheer quantity of sunlight striking the planet worked to evaporate the oceans of ancient Venus. Subsequently, ultraviolet light broke down the resulting water vapor particles into their constituent elements. Once the majority of the hydrogen had escaped into space, all that remained was a dense, carbon-dioxide-dominated atmosphere shrouding the lifeless planet we see today.

The evidence for the habitability of Venus-like planets could help inform the search for exoplanets with the potential to harbor life. These exoplanets may now present a more attractive prospect for the next generation of ground-based and orbital observatories, including the much anticipated James Webb Space Telescope.

Source: NASA

4 comments
4 comments
Digitalclips
I am sure scientist reading this is thinking the same thing .... "Did a life form evolve far enough to have their own industrial revolution, based on fossil fuels?"
GarthBock
This indicates that we must loose the Earth-centric notion that to be an inhabitable exoplanet it has to rotate on a 24 hour basis and be the same size as us.
habakak
If intelligent live evolved there, it would not have been easy to got to where we are. Think about having a day 2808 hours long. And how long would your night be? You would have to go underground and in caves to find respite from the long days, but the long night would have been a lot harder to survive. Think about finding and storing enough food and fuel for a fire during the 2808 hours of day light to survive the following possibly longer period of total darkness and cold.
Not that I believe this model to be correct. Models are always incomplete and based on massive unknowns. And to believe in the accuracy of a model to try and determine an alien landscape based on reconstructing a climate thousands or billions of years ago with such an incomplete model is absurd at best. There are just too many unknowns in a complex system to predict the future and now we are trying to 'predict' the past for an ALIEN PLANET? Laughable.
Russ
New NASA report shows Venus was once a warm water world, but it slowly fell inside the Solar Systems Goldilocks Zone, it's plankton filled oceans fought to keep it cool but after 2 billion years its oceans boiled away. This is a lesson for Venus' Sister Planet - Earth. http://russgeorge.net/2016/08/12/without-plankton-earth-will-become-like-venus-not-mars/