Moon Dike Map This map of one side of the moon shows the
location of some of the giant dikes identified by NASA's GRAIL
mission. These dikes are solidified magma filled cracks with
lengths up to 300 miles (480 kilometers) and widths of up to 24
miles (40 kilometers). The formation of these dikes tells us
that the moon expanded during the first billion years of its
history, with its radius increasing by as much as 3 miles (5
kilometers). This early expansion of the moon was previously
predicted by theoretical models, and is now confirmed by GRAIL
gravity data. The base map consists of topographic shaded data
from NASA's Lunar Reconnaissance Orbiter's Lunar Orbiter Laser
Altimeter. Image credit: NASA/JPL-Caltech/CSM