Moon Differences

21 May 2019

Sent in by William - go to https://phys.org/news/2019-05-giant-impact-difference-moon-hemispheres.html ... a giant impact caused the differences between the two hemispheres of the Moon. The topographic evidence, crustal thicknesses, the thorian distribution, etc, show a dramatic difference between the nearside and the farside. The farside is heavily cratered but the nearside, the earth facing side of the Moon, has lower lying open basins. The differences are being blamed on a collision with a dwarf planet - suitable relegated to the early solar system period (at the bottom of the drawer, hidden beneath the socks and handkerchiefs). The gravity data gleaned from the GRAIL mission has made measurements of crustal thickness, amongst other things. The data was then used in a computer simulation (rather a lot of computer simulations in order to find one to fit the situation). They simulated impacts and it was found that a large object was required in order to create the rugged topographic landscape of the farside of the Moon. In the impact it is theorised that a lot of material, as in a vast amount, would have been thrown upwards, only to fall back on to the surface, burying the primordial crust (with another layer, hence the crustal thickness on the far side). Amazing what can be learnt from a computer simulation - but is it what really happened.