From Dragon Ball Wiki, the ''Dragon Ball'' encyclopedia
The Moon (月, Tsuki) is a celestial object revolving around Earth in the Dragon Ball universe, just as its real world counterpart. Its significance is that it has made some Saiyans transform into their Great Ape forms, and it has been destroyed twice and recreated once.
 Role of moons in the Dragon Ball series
 Prior to Dragon Ball
 Boss Rabbit
 Castle Pilaf
 21st Tenkaichi Tournament
 The Moon revived
It was not mentioned, but the Moon must have been recreated during Goku's training in Kami's Lookout since Goku mentions in the 23rd Tenkaichi Tournament that his tail was removed so that the Moon could be recreated. The Moon is also seen later, indicating that it has been recreated.
 Gohan's metamorphosis
 The moon's image
Goku's Attack Ball projected the image of a moon which again made Gohan transform into a Great Ape. When Piccolo destroyed the Attack Ball, the projector was destroyed.
 Known residents of Earth's moon
 Moons of other planets
Most moons or satellites of other planets have been shown whenever the planet was shown, and without much significance. The moons of Vegeta and of Kanassa, however, were important as the Saiyans had used them to transform.