Why is Earth the only planet that has continents?

New research sheds light

In our limited knowledge of the universe so far, Earth is the only planet with continents. How they formed and evolved is not clear, but we do know that at some point in the distant past, all the continents were gathered together in one single land mass known as Pangaea. But what caused them to split apart to create the world map we know today?

A new study from Curtin University in Australia shows that collisions with huge meteorites played an important role. Scientists have found in Western Australia crystals of zircon, a mineral that has remained stable in the Earth’s crust for billions of years. The zircon contained evidence of ancient collisions with meteorites, before the continents broke apart.

By studying the composition of the oxygen isotopes found in these crystals, we saw a process taking place in the molten rocks that began near the surface and continued deeper, consistent with the geological effects of massive meteorite impacts. Our research is the first irrefutable evidence that the processes that eventually formed the continents began with massive meteorite collisions, similar to the one that wiped out the dinosaurs, but happened billions of years earlier.

According to scientists, the meteorite bombardment heated the planetary crust. When it stabilized, much later it evolved into today’s continents. Countless meteorites have struck the Earth, many more than the number of continents. However, only the largest of them could produce enough heat to start this process.

The research was published in Nature .