Open the mystery of the

It is difficult to understand why Mars' poles look so different now that may have been elucidated.

The northern hemisphere of Mars is a giant sunken basin, which may have once contained an ocean (this idea is very old, but no one has tried to make real calculations). In contrast, the southern hemisphere is a high mountain hole with a crater, with a difference of up to 8,000 meters above the north.

The new study predicts a large meteorite has crashed into Mars, creating a giant scar in the northern hemisphere.(Photo: BBC)

The new US study predicts that a sky rock has bumped into the planet, creating a sudden difference between its two halves. That sky rock could be roughly the size of our moon and was thrown into the northern hemisphere, scientists say.

The collision with energy equivalent to 1 million billion atomic bombs fell on Nagasaki in 1945.

The new study speculates that this is the largest meteor scar ever known in the solar system. It also challenged another hypothesis, arguing that Mars's "two-sided" was the product of a powerful volcanic eruption of 3.8 billion years ago.