Somewhere roughly in the middle of the Indian Ocean is the deepest dent in Earth’s gravitational field – the place where Earth’s gravitational pull is the weakest. That’s because there is less mass under that spot on our planet – but why?
Many possible explanations have been put forward, but proving any of the theories has turned out to be tricky. Now Debanjan Pal and Attreyee Ghosh, of the Centre for Earth Sciences at the Indian Institute of Science in Bengaluru, India, think they have the answer. They reconstructed the last 140m years of plate tectonic movements and the stirring in the underlying mantle that accompanied the rearrangement of Earth’s crustal jigsaw.
