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LOS ANGELES (AP) — Why is Mars two-faced?
Scientists say fresh evidence supports the theory that a monster impact punched the red planet, leaving behind perhaps the largest gash on any heavenly body in the solar system.
Today, the Martian surface has a split personality.
The southern hemisphere of Mars is pockmarked and filled with ancient rugged highlands. By contrast, the northern hemisphere is smoother and covered by low-lying plains.
Three papers published in today’s journal Nature provide the most convincing evidence yet that an outside force was responsible.
According to the researchers, an asteroid or comet whacked a young Mars some four billion years ago, blasting away much of its northern crust and creating a giant hole over 40 per cent of the surface.
New calculations reveal the crater known as the Borealis basin measures 8,500 kilometres across and 10,600 kilometres long — the size of Asia, Europe and Australia combined. It’s believed to be four times bigger than the current titleholder, the South Pole-Aitken basin on Earth’s moon.
Astronomers have long puzzled over Mars’ landscape ever since images beamed back in the 1970s showed different-looking halves.