* Astronomy

Nasa's Grail twins to make gravity maps

The latest spacecraft to go to the Moon have launched from Florida.
Nasa is sending twin probes called Grail to map tiny variations in the pull of gravity around the lunar body.
The information should give scientists fresh insight into the internal structure of Earth's satellite.
This will help explain many mysteries, such as why the farside of the Moon looks so different from that of the nearside with its great swathe of dark volcanic plains, or maria.
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