Man in the moon mystery solved

No face looks out from the dark side because crust is too tough

A "man in the moon" gazes down on Earth but there is no matching face on the dark far side of the moon. And scientists now believe they know the reason why, solving a 57-year-old mystery.

The face we see is made by huge patches of grey rock put there when meteorites punched holes in the moon’s crust, causing lava flows that spread to form flat seas of basalt.There were no lava flows on the hidden side despite it also being pummelled by meteorites.

Astrophysicists from Pennsylvania State University yesterday published research findings that put the lack of a face down to the way the moon formed billions of years ago, with the far side left with a extra thick crust that could not be punched through by later meteorites.

Dick Ahlstrom

Dick Ahlstrom

Dick Ahlstrom, a contributor to The Irish Times, is the newspaper's former Science Editor.