Scientists Say Life Could Exist on 'Snowball' Planets

Tuesday, 13 August 2019 - 1:03PM
Alien Life
Astrobiology
Tuesday, 13 August 2019 - 1:03PM
Scientists Say Life Could Exist on 'Snowball' Planets
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NASA
It seems intuitive, even for humans. If a planet is too close to its sun, there will be no chance of liquid water, which is, as far as we know, a universal requirement for life. If a planet is too far from its sun, then any water may take the form of ice at super-low temperatures that are as inhospitable to life as planetary furnaces. Indeed, it has long been assumed that for a planet to have any chance whatsoever of supporting life, it had to be within the habitable zone of its sun: the range of distances that all for surface water to exist as a liquid. It turns out that may not be the case. New research published in the American Geophysical Union's (AGU) Journal of Geophysical Research: Planets indicates that some "snowball" planets could have life-supporting conditions in their equatorial regions. 


The research challenges the long-held assumption that snowball planets are uniformly frozen: that they remain below freezing all throughout their surfaces due to a lack of carbon dioxide, which traps heat in the atmosphere to warm planets (which is why CO2 emissions are of concern when it comes to climatology). "You have these planets that traditionally you might consider not habitable and this suggests that maybe they can be," said University of Toronto astronomer and physicist Adiv Paradise, lead author of the paper. 


According to the researchers,


"As the chemical process by which CO2 is removed from the atmosphere and bound in surface rocks relies on warm temperatures and liquid water and therefore would not happen in globally cold conditions, this has also led to the conclusion that snowball events should be temporary, coming to an end when volcanoes release enough accumulated CO2 to warm the planet enough to melt the ice. We ran several thousand three‐dimensional computer simulations of Earth‐like climates and
found that if there are inland areas of dark, bare ground under enough sunlight, those regions can be warm enough for liquid water and life without causing the sea ice to retreat. This suggests that snowball planets should not be excluded as inhospitable to life and that on some planets the burial of CO2 in surface rocks in these areas could balance volcanic emissions, resulting in permanent snowball conditions."


For those who are skeptical, it's worth pointing out the Earth has gone through a snowball phase or two in its life and look where we are now: positively teeming with life of all shapes, sizes, and smells. "We know that Earth was habitable through its own snowball episodes," Paradise said in a statement, "because life emerged before our snowball episodes and life remained long past it. But all of our life was in our oceans at that time. There's nothing about the land."


We hope you're comforted by the knowledge that somewhere in the far reaches – or perhaps even just a few light years away – of the galaxy there could exist a species so resilient that it is simply sleeping, hibernating, waiting for the slow seep of carbon dioxide to warm its mega-planet's surface just enough to wake it in time to seek a new home: ours.
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NASA
Alien Life
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