Solving A Lunar Mystery Almost As Old As The Moon Itself! The rectangular pattern, with its straight sides and angular corners, weakens the theory that Procellarum is an old impact basin. This is because such a mighty impact would form a circular basin. Instead, the recent study indicates that processes occurring deep beneath the lunar surface dominated the formation of this unique region.
However, the astronomers will require more HST observations in order to obtain accurate measurements in order to determine if the moon's orbit is circular or elliptical. Preliminary estimates suggest that if the moon is in a circular orbit, it finishes a circle around Makemake in 12 days or longer.
"Since time immemorial, humanity has looked up and wondered what made the man in the Moon. We know the dark splotches are large, lava-filled, impact basins that were created by asteroid impacts about four billion years ago. GRAIL data indicate that both the near side and the far side of the Moon were bombarded by similarly large impactors, but they reacted to them much differently," noted Dr. Maria Zuber, GRAIL principal investigator, in a November 7, 2013 NASA Jet Propulsion Laboratory (JPL) Press Release. Dr. Zuber is of the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts. The JPL is located in Pasadena, California.