Why Earth Has Life and Venus Doesn't: Planet Conditions for Habitability

First Posted: Jul 22, 2015 09:13 AM EDT

What caused Earth to develop life and not Venus? Scientists have taken a closer look to find out why Earth managed to sustain life while Mars and Venus did not.

In this latest study, the researchers took a look at Earth. On our planet, shifting tectonic plates cause regular overturning of Earth's surface, which steadily cools the underlying mantle, maintains the planet's strong magnetic field and stimulates volcanic activity. Erupting volcanoes release greenhouse gases from deep inside the planet and regular eruptions help to maintain the habitable climate on our planet.

"The events that define the early formation and bulk composition of Earth govern, in part, the subsequent tectonic, magnetic and climatic histories of our planet, all of which have to work together to create the Earth in which we live," said Mark Jellinek, one of the researchers, in a news release. "It's these events that potentially differentiate Earth from other planets."

Venus is similar to Earth in size, mass, density, gravity and composition. However, Venus is in a climate catastrophe with a thick carbon dioxide atmosphere and surface temperatures that reach about 470 degrees Celsius.

The fact is that Earth could have easily ended up like Venus. However, a key difference may be differing extents of impact erosion. With less impact erosion, Venus would cool episodically with catastrophic swings in the intensity of volcanic activity, driving dramatic billion-year-long swings in climate.

"We played out this impact erosion story forward in time and we were able to show that the effect of the conditions governing the initial composition of a planet can have profound consequences for its evolution," said Jellinek. "It's a very special set of circumstances that make Earth."

The findings are published in the journal Nature Geoscience.