Researchers used to think that icy planets are too cold to support life, but researchers now suggest that these frozen worlds may have livable areas, where alien life could potentially thrive.

Snowball planets are Earth-like planets with oceans frozen to the equator. Scientists have long thought that these alien worlds are hostile to life because of the extreme cold.

In a new study, Adiv Paradise, an astronomer and physicist at the University of Toronto, and colleagues found that some snowball planets could be habitable. These frozen Earths may have areas of land near the equator that reach livable temperatures.

The researchers used a computer program to simulate different climate variables on theoretical snowball planets.

One particular variable they were interested in was carbon dioxide, a greenhouse gas largely attributed to Earth’s climate change. It traps heat and keeps a planet in temperate climate range. Without carbon dioxide, planets cools and oceans freeze.

Snowball planet
Pictured: An artist's concept of an icy planet. Pixabay

Planets become snowballs as a result of atmospheric carbon dioxide levels dropping too low from erosion and rainfall. Water absorbs carbon dioxide and turns it into carbonic acid that reacts with the rocks on the ground during erosion.

The interaction causes the carbonic acid to break down more and binds with minerals that are transported to the oceans and eventually stored in the seafloor.

Researchers once thought that the removal of carbon dioxide from the planet’s atmosphere would stop during the snowball phases because the surface water was frozen.

Simulations, however, revealed that some snowball planets continue to lose carbon dioxide even after they have frozen.

This suggests that these planets would have some non-frozen ground and occasional rainfall for water to keep removing carbon dioxide from the atmosphere.

Some of the warmer snowball planets the researchers simulated had land areas warm enough to hold liquid and life even when the oceans were frozen to the equators.

Paradise and colleagues found land areas in the center of the continents far from the frozen ocean that could reach above 10 degrees Celsius, or 50 degrees Fahrenheit. This temperature is warmer than the lowest temperature at which life can survive and reproduce.

“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,” the researchers wrote in their study published in the Journal of Geophysical Research.

“This suggests that snowball planets should not be excluded as inhospitable to life.”

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