New research shows that Mars spewed so much lava 3.5 billion years ago that its surface swivelled and displaced its weight.
“If a similar shift happened on Earth, Paris would be in the polar circle,” lead researcher Sylvain Bouley from the Université Paris-Sud told the Guardian. “We’d see northern lights in France, and wine grapes would be grown in Sudan.”
According to the research, this would explain many of Mars’s mysteries, such as its underground water ice and its dry riverbeds. “Scientists couldn’t figure out why the [dried up] rivers were where they are. The positioning seemed arbitrary,” Bouley told the Guardian. “But if you take into account the shift in the surface, they all line up on the same tropical band.”
The findings suggest that the volcanic upheaval on Mars lasted for a couple of hundred years, and tilted its surface by 20 to 25 degrees.
The lava created what is known as the Tharsis dome, more than 5000 square kilometres (2000 square miles) wide and 12km (7.5m) thick. Mars is half of earth’s size in diameter. The weight of the Tharsis lava layer was so heavy that it caused Mars’ top two layers, the crust and the mantle, to swivel around. If it were to be removed, Bouley’s team speculate that Mars’s axis would swivel again.
The findings were published in Nature, and are a major discovery in what has become a hot area for research as the race to fly to Mars draws closer.