It has been decades since man has walked on the moon. Scientists have made an important discovery about the moon recently using rocks recovered by astronauts from the Apollo missions of the 1970's.
One of the big questions that have stumped scientists since the early exploration of the moon is why lunar rocks are magnetic. Earth's magnetic field is produced by its rotating, iron core; something that the moon lacks.
Scientists at MIT believe they have finally solved the mystery. The scientists believe that about 4.2 billion years ago the moon had a liquid core that produced a strong magnetic field, similar to what the Earth has today.
Evidence of the molten core theory was found by analyzing the oldest of the moon rocks, which were not subjected to major shocks from impacts on the moon's surface. These later impacts erase all evidence of earlier magnetic fields.
The particular rock used by the researchers is one collected by astronaut Harrison "Jack" Schmitt who is the only geologist to ever walk on the moon. Ben Weiss, one of the MIT researchers, told Space.com, "Many people think that it's the most interesting lunar rock."
Weiss and other team members used a commercial rock magnetometer fitted with a special robotic arm to study the faint traces of magnetism in the rock. The researcher say that the test results allowed them to rule out other possible sources of magnetic traces in the rock, such as the magnetic fields that are briefly generated by the impacts on the moon. The magnetic fields generated by these collisions reportedly generate mini magnetic fields lasting mere seconds up to a full day for very large impacts.
The readings the scientist made show that the rock was in the presence of a magnetic field for millions of years and that the magnetic fields must have come from a magnetic dynamo creating by a rotating core. The magnetic field on the moon is believed to have been about 1/50th of the magnetic field the earth has today.
Space.com says that the findings fit into the theory that the moon was created when a Mars-sized body collided with the Earth, blasting much of its crust into space where it clumped together and formed the moon.