51:57Why Is The Far Side Of The Moon So Different? | Science's Greatest Mysteries Episode 1
Spark's Science's Greatest Mysteries opens with the far side of the Moon, a hemisphere that looks nothing like the one we always see. Starting from Luna 3's shocking 1959 photographs, the film walks through the three great clues to the puzzle: the missing dark maria, the near side's KREEP chemistry from the Apollo rocks, and the GRAIL gravity map showing a crust about 30 kilometers thick on the near side and 50 kilometers on the far side. It then lays out three competing explanations that all begin with the giant impact that formed the Moon: uneven cooling next to a red hot young Earth, a second giant impact that flung the near side onto the far side, and a lost companion moon that merged with ours in a slow motion splat. It closes with the new evidence, frozen Apollo samples and China's Chang'e far side landings, that may finally settle which one is right.