But what about the features that are miles and miles long with unchanging widths?
Space.com wrote:Many mysteries remain about the magnetic field of the moon, such as what powered it and when it ended, the scientists added.
But scientists were uncertain whether the moon generated a magnetic field the same way Earth does, or if the magnetic fields seen on the moon were instead produced by outside forces. For instance, cosmic impacts on the moon could have sparked super-heated plasma that generated strong, brief magnetic fields, explaining the magnetized rocks the astronauts discovered.
In the past six years or so, however, a new generation of scientific techniques and computer simulations has now made a strong case that the moon may have had a magnetic core like Earth's.
Magnetic fields are generated by electric currents.
"We think planets generate magnetic fields by moving electrically conducting fluids inside them," said study co-author Benjamin Weiss, a planetary scientist at MIT. Flowing metal in Earth's core makes the heart of the planet a dynamo — a generator of electrical current — and this dynamo generates Earth's magnetic field.
If the moon had a dynamo that generated a magnetic field, that could yield key insights into its hidden inner structure.
"The moon is intermediate between a planet and a small body like an asteroid, so establishing whether the moon had an ancient dynamo could help show that it was a highly evolved body differentiated into layers like Earth," he added. "This would tell you about the origin of the moon — some models say the moon started off cold and unmelted, while others suggest it was created from a giant impact and predict it should have been hot."
Q. Why is it so surprising that a lunar dynamo may have been so intense and long-lived?
A. Both the strong intensity and long duration of lunar fields are surprising because of the moon's small size. Convection, which is thought to power all known dynamos in the solar system today, is predicted to produce surface magnetic fields on the moon at least 10 times weaker than what we observe recorded in ancient lunar rocks.
Nevertheless, a convective dynamo powered by crystallization of an inner core could potentially sustain a lunar magnetic field for billions of years. An exotic dynamo mechanism that could explain the moon's strong field intensity is that the core was stirred by motion of the solid overlying mantle, analogous to a blender. The moon's mantle was moving because its spin axis is precessing, or wobbling, and such motion was more vigorous billions of years ago, when the moon was closer to the Earth. Such mechanical dynamos are not known for any other planetary body, making the moon a fascinating natural physics laboratory.
This year on the Sunday before the Feast of Saint John the Baptist, after sunset when the moon was first seen, a marvelous sign was seen by five or more men sitting facing it. Now, there was a clear new moon, as was usual at that phase, its horns extended to the east; and behold suddenly the upper horn was divided in two. Out of the middle of its division a burning torch sprang, throwing out a long way, flames, coals and sparks. As well, the moon's body which was lower, twisted as though anxious, and in the words of those who told me and had seen it with their own eyes, the moon palpitated like a pummeled snake. After this it returned to its proper state. This vicissitude repeated itself a dozen times or more, namely that the fire took on tormented forms variously at random, and afterwards returned to its prior state. Even after these vicissitudes, from horn to horn, that means along its length, it became semi-black. This to me who writes this was told by those men who with their own eyes saw it, and who are willing to swear an oath that they have not added to nor falsified the above written.
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