The mysterious magnetic rocks gathered on the Apollo expedition have finally been explained.

pixabay.com

For the past 50 years, scientists have been baffled by the rocks brought back from the Apollo missions.

Until now, scientists have been stumped as to why some lunar rocks brought back to Earth from the lunar surface appear to have been produced in a magnetic field as powerful as ours.

The churning movement of material in planetary bodies' electrically conductive molten cores generates magnetic fields. In contrast to Earth's dense and mostly frozen interior, there is just a small area of the non-magnetic moon's interior that has a liquid or molten state. After its formation some 4.5 billion years ago, scientists believe the moon's interior cooled rapidly and uniformly, meaning it doesn't have a strong magnetic field, which many believe it never had.

As a result, how could some of the three billion-year-old rocks collected from NASA's Apollo missions seem like they were produced in an environment with a geomagnetic field so strong it may rival Earth's? In contrast, others had no magnetic fingerprints at all.

Scientist Alexander Evans of Brown University said that "everything that we've understood about how planetary cores create magnetic fields tells us that an object as large as the moon should not be able to generate a field as strong as Earth's."

Over the past 50 years, scientists have come up with several possible reasons for this strange difference. Or, perhaps the moon's gravitational connection with Earth gave it an excessive wobble, sloshing around its cooling interiors to raise its magnetic field after it formed. Another possibility is that asteroids pelted the moon with so many jolts that the core of the moon began to tremble.

New findings from Stanford geophysicist Sonia Tikoo-Schantz and Evans have been published in the journal Nature Astronomy on Jan. 13.

Evans suggested getting a high-intensity magnetic field sporadically rather than continually over billions of years.

For the first few billion years of its existence, the moon was a sea of molten rock, with only a small iron core remaining inside, surrounded by a partially molten outer core. There was little convection between the core and mantle, which is important to keep in mind while studying the moon's interior. As a result of the moon's molten interior being incapable of churning, its magnetic field could not have been stable.

On the other hand, researchers believe that the moon may have generated a powerful intermittent field. Minerals in the moon's heated magma would have cooled at varying rates as the moon cooled. Magma that contained titanium and other heat-producing elements such as potassium (thorium), uranium, and olivine (pyroxene) would have risen to the surface of the Earth's crust and then lost its heat when it cooled. Many solids below the titanium-laden rock would sink slowly but steadily toward the molten outer core as it cooled to crystallization.

The moon's sinking titanium was estimated to have broken into chunks as small as 37 miles (60 kilometers) across and sunk at various rates over roughly a billion years by studying the known composition of the moon and making a calculated guess on its past mantle viscosity—or how easily its magma could churn. These cold titanium fragments would have re-ignited the core's dormant convection currents each time they impacted the hot outer core, igniting the moon's magnetic field for a brief period.

Evans likened it to a drop of water splashing on a hot pan. "When anything extremely cold comes in contact with the core, a large amount of heat might abruptly escape. That causes the core to churn, resulting in the powerful magnetic fields you see from time to time."

To understand why various lunar rocks have distinct magnetic fingerprints, it is necessary to accept that the magnetosphere on the moon is in constant flux.

If this pattern can be detected, experts say they will conduct tests on Apollo's lunar rocks to see whether they can be found. There may finally be an end to the riddle of the moon's magnetism if bursts of strong magnetic signals are identified among weak magnetic evidence.

Reference : https://www.livescience.com/moon-apollo-rock-mystery-explained

Image source : https://pixabay.com/id/illustrations/benda-terbang-aneh-pegunungan-1265186/

What was collected during the Apollo missions?

What rocks did Apollo 11 bring back?

What happened to the Moon rocks brought back by NASA?

Where are the Moon rocks from the Apollo missions?

Why did the astronauts bring rocks back from the Moon?

What was learned from moon rocks?

Who left a Bible on the Moon?

What is Moon rock drug?

How much is a Moon rock worth?

What happens if you touch a moon rock?

Who Stole the Moon rocks?

Can you touch a moon rock?