We do not have a definitive answer to this question. Scientists are still researching this question as of 2015. However, if extraterrestrial, it certainly was not ONE extraterrestrial body.
Comets, because they are made from ice and dirt.
it is water cycle
70% or 80% of water covers the earths surface
3/4 of the earth's surface is water.
Indian Ocean covers 20% of water on the earths surface.
69%
about 30%
the sun
Water.
the water cycle
30%
Ground water.