What is the result of the Mars two-faced riddle and when was it solved?
Here is an article posted on the UK’s Daily Mail website: A giant crater made by an asteroid or comet is the reason Mars is so lopsided, scientists said today. The impact gouged out a hole 5,200 miles across and 6,500 miles long, leaving a basin covering 40 per cent of the red planet, researchers reported in the journal Nature. The depression is the size of the combined areas of Asia, Europe and Australia, which makes it by far the largest crater in the solar system. In 1984 scientists proposed an impact had caused the two-faced appearance of Mars with two strikingly different kinds of terrain in its northern and southern hemispheres. This fell into disfavor because the ‘Borealis Basin’ didn’t seem to fit the expected round shape However, the latest three studies said some of the basin’s edges have been erased by volcanic activity. “We haven’t proved the giant-impact hypothesis, but I think we’ve shifted the tide,” said Jeffrey Andrews-Hanna, a researcher at the Massachusetts Institute
