According to the latest estimates by a team of researchers with the Technische Universität Berlin, it might have taken ten times longer than previously thought for the early Moon to transform from a ball of super-heated magma into its current form.

The oldest rock found on the Moon, brought to Earth by the Apollo 14 mission, has been dated to 4.51 billion years old, comparing to the estimated 4.54 billion years estimated for the age of the Earth. But minerals can go back only as far as the moment when those minerals formed. To date the Moon, scientists need to know how much time elapsed until the magma ocean solidified, explains Sky & Telescope.

Maxime Maurice and his colleagues at the German university have developed a new thermal evolution model — a detailed computer simulation — to reconstruct the first 200 million years of lunar evolution. Their studies identified two previously underappreciated dynamics: the insulating effect of the primordial lunar crust, and mantle convection that probably started even before the magma ocean completely solidified.

It has been long known that the early Moon formed a crust made of a light mineral called pagioclase, which floated atop the magma ocean. That crust turned out to be an excellent insulator. While previous studies had accounted for that effect, Maxime concluded the insulating effect had been under-estimated.

The other factor was mantle convection. Summarizes Sky & Telescope:

The lunar magma ocean solidified from the bottom up because high pressure at depth forced the magma to solidify even at high temperatures. This process likely solidified 80% of the magma ocean within 1,000 years of the Moon’s formation. If mantle convection started at this point, it could have allowed heat to continue flowing from the depths toward the surface, keeping the magma ocean hot and molten.

On Earth, mantle convection creates the magma that feeds volcanoes. “In this case, it would be exactly the same, but the volcanoes would have spilled their lava into the magma ocean,” Maurice explains.

Until now, van Westrenen says, most lunar evolution scenarios assumed that mantle rocks didn’t start moving until the magma ocean had completely solidified.

According to van Westrenen, the combination of these two processes makes a huge difference for the longer-term survival of the magma ocean.

A slowly crystallizing magma ocean could require a reinterpretation of mineral isotope dating of many lunar samples, and thus for the aging of the Moon-forming impact. The bottom line, the Moon may be 100 million years younger than commonly postulated.

The formation of ancient rocks on the Moon may be directly linked to large-scale meteorite impacts, concludes a group of international scientists led by the Royal Ontario Museum after research a unique rock collected by NASA astronauts during the 1972 Apollo 17 mission to the Moon. The rock contains mineralogical evidence that it formed at incredibly high temperatures, in excess of 2300 °C/ 4300 °F, that could have been achieved by the melting of the outer layer of a planet in a large-impact event, reports Science Daily.

Researchers discovered in the rock the presence of a mineral known as baddeleyite, a stable phase arising from cubic zirconia, commonly used on earth as a substitute for diamonds in jewelry, which could have been formed only in rocks heated to above 2300 °C. While examining the structure of the crystal, the researchers measured the age of the grain, which reveals the baddeleyite formed over 4.3 billion years ago. Given that the high-temperature cubic zirconia phase must have formed before this then, they concluded that large impacts were critically important to forming new rocks on the early Moon.

“Rocks on Earth are constantly being recycled, but the Moon doesn’t exhibit plate tectonics or volcanism, allowing older rocks to be preserved,” explains Dr. Lee White, Hatch Postdoctoral Fellow at the Museum. “By studying the Moon, we can better understand the earliest history of our planet. If large, super-heated impacts were creating rocks on the Moon, the same process was probably happening here on Earth.”

Adds Dr. James Darling, a reader at the University of Portsmouth and co-author of the study. “These unimaginably violent meteorite impacts helped to build the lunar crust, not only destroy it.”

Once upon a time the Moon had a magnetic field, and it was likely stronger than Earth’s is today. That field, generated by a powerful dynamo in the Moon’s core, petered out about one billion years ago.

The latest theory, propagated by MIT scientists in the journal Science Advances, suggests that crystallization of the Moon’s inner iron core stirred the electrically charged fluid and produced the dynamo.

“The magnetic field is this nebulous thing that pervades space, like an invisible force field,” says Benjamin Weiss, professor of earth, atmospheric, and planetary sciences at MIT. “We’ve shown that the dynamo that produced the moon’s magnetic field died somewhere between 1.5 and 1 billion years ago, and seems to have been powered in an Earth-like way.”

Most studies of lunar magnetism have been based on rock samples from the Apollo missions; most of the ancient rocks are estimated to be thee to four billion years old. When they were spewed out as lava, their microscopic grains aligned in the direction of the Moon’s magnetic field. Lunar rocks whose magnetic histories began less than three billion years ago do not show such alignment, which suggests that lunar vulcanism had largely ceased by that time.

The MIT scientists theorize that the early Moon was much closer to the Earth than it is today, and much more susceptible to its gravitational effects. In a phenomenon known as “precession,” the solid outer shell of the cooling Moon wobbled in response to the Earth’s gravity. The wobbling stirred up the fluid in the core, the way swishing a cup of coffee stirs up the liquid inside, explains MIT News.

As the moon moved slowly away from the Earth, the precession effect decreased, weakening the dynamo and the magnetic field. About 2.5 billion years ago, core crystallization became the dominant mechanism by which the lunar dynamo continued, producing a weaker magnetic field that continued to dissipate as the moon’s core eventually fully crystallized.

The early Moon likely contained significant volumes of water mixed into its global ocean of molten rock, theorize scientists from VU Amsterdam.

According to the conventional view, the Moon was formed by a collision of a small planetary-sized body with the young Earth that created a swirling mass of debris from which the Earth and the Moon condensed. In a process parallel to Earth’s, the Moon started as a mass of molten rock that slowly cooled over the ages. As it cooled, different minerals solidified at different temperatures and depths.

The Dutch scientists  began asking how various mineral mixes behaved under extreme temperatures and pressures. Their models indicate that the Moon must have started with water mixed with the magma. Explains Ars Technica:

“How do you model an entire ocean of molten rock? You start with the known composition of the Moon and use that to create a mix of the appropriate minerals. Then you expose those minerals to extreme pressures and temperatures well beyond the melting point of rock. For these experiments, the temperatures ranged up to 1,550 degrees Celsius. Since the magma ocean was potentially hundreds of kilometers deep (current estimates range from 400 to 1,000 kilometers), pressures ranged up to 3 GigaPascals, which is nearly 30,000 atmospheres.” more “Early Moon Had More Water than We Thought”