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 modelling, theplanet Venus could have once been habitable, hosting a shallow-waterocean, and surface temperatures hospitable to life. The simulationsare based on present-day observations of Venus, paired with dataharvested 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 ownplanet, has led to a runaway greenhouse effect, resulting in surfacetemperatures of 864 ºF(462 ºC).

However, it is possible that, in itsancient past, this hellish world could have sincerely deserved themoniker of Earth's twin. In the 1980s NASA's Pioneer spacecraftobserved clues that a water ocean may once have existed on Venus.Now, a team of scientists from NASA's New York-based GoddardInstitute for Space Studies has run computer simulations designed tomodel Venus' ancient atmosphere, and come up with some surprisingresults.

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

Digital Venus was given an atmospheresimilar to that of present day Earth, and furnished withtopographical features based on data harvested by NASA's Magellanmission that visited the planet in the 1990s. The researchers thenfilled the low-lying areas of the planet with a shallow ocean,leaving only the highlands exposed.

According to the team, landmasses onancient Venus would have been much dryer than their Earthlyequivalent. This fairly mundane characteristic could have played avital part in keeping the planet's greenhouse gas problem at bay, asless water vapour would escape from the ground via evaporation.

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

The slow spin of the planet, whichwould expose areas of the surface to the glare of the Sun for monthsat a time, allowed the heat from our star to evaporate enough waterto create a kind of cloud shield. This barrier mitigated some of ourSun's heating influence, which, whilst younger and less hot in thesimulations than it is today, would still have bathed the planet in40 percent more sunlight than that received by present-day Earth.

Itis estimated that this Earth-like Venus could have remained habitable in this way foraround 2 billion years.

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

The evidence for the habitability ofVenus-like planets could help inform the search for exoplanets withthe potential to harbor life. These exoplanets may now present amore attractive prospect for the next generation of ground-based andorbital observatories, including the much anticipated James Webb Space Telescope.

Source: NASA

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/