Old moon, young crust: Violent volcanism may mean the moon is much older than previously thought

After its formation, the moon may have been the scene of such immense volcanic activity that its entire crust melted several times and was completely churned through. At that time, the moon orbited significantly closer to Earth than today. The resulting tidal forces heated up its interior and thus powered the violent volcanism. Only Jupiter's moon Io, by far the most volcanically active body in the solar system, offers comparable conditions.