New Origin Theory –The Moon Formed Inside a Seething, Spinning Cloud of Vaporized Earth

Moon-rise
 

"The new work explains features of the Moon that are hard to resolve with current ideas," said Sarah Stewart, professor of Earth and Planetary Sciences at UC Davis. "The Moon is chemically almost the same as the Earth, but with some differences," she said. "This is the first model that can match the pattern of the Moon's composition."


A new explanation for the Moon's origin has it forming inside the Earth when our planet was a seething, spinning cloud of vaporized rock, called a synestia. The new model led by researchers at the University of California, Davis and Harvard University resolves several problems in lunar formation and is published Feb. 28 in the Journal of Geophysical Research – Planets.

 

Current models of lunar formation suggest that the Moon formed as a result of a glancing blow between the early Earth and a Mars-size body, commonly called Theia. According to the model, the collision between Earth and Theia threw molten rock and metal into orbit that collided together to make the Moon.

The new theory relies instead on a synestia, a new type of planetary object proposed by Stewart and Simon Lock, graduate student at Harvard and visiting student at UC Davis, in 2017. A synestia forms when a collision between planet-sized objects results in a rapidly spinning mass of molten and vaporized rock with part of the body in orbit around itself. The whole object puffs out into a giant donut of vaporized rock.

 

164075_web

Synestias likely don't last long – perhaps only hundreds of years. They shrink rapidly as they radiate heat, causing rock vapor to condense into liquid, finally collapsing into a molten planet.

"Our model starts with a collision that forms a synestia," Lock said. "The Moon forms inside the vaporized Earth at temperatures of four to six thousand degrees Fahrenheit and pressures of tens of atmospheres."

An advantage of the new model, Lock said, is that there are multiple ways to form a suitable synestia – it doesn't have to rely on a collision with the right sized object happening in exactly the right way.

Once the Earth-synestia formed, chunks of molten rock injected into orbit during the impact formed the seed for the Moon. Vaporized silicate rock condensed at the surface of the synestia and rained onto the proto-Moon, while the Earth-synestia itself gradually shrank.

Eventually, the Moon would have emerged from the clouds of the synestia trailing its own atmosphere of rock vapor. The Moon inherited its composition from the Earth, but because it formed at high temperatures it lost the easily vaporized elements, explaining the Moon's distinct composition.

The Daily Galaxy via University of California Davis

Image credit: Image by Sarah Stewart/UC Davis based on NASA rendering

Most Popular Space & Science Headlines

"Alien Minds" –'Artificial Intelligence Is Already Out There, and It's Billions of Years Old' (VIDEO)

 "300-Million Nuclear Bombs" –New Insights Into Global Impact of Titanic Chicxulub Mass-Extinction Event

Stephen Hawking: Wake Up, Science Deniers! –"Earth is Morphing into Venus" (WATCH Today's 'Galaxy' Stream)

"Evolutionary Leap?" AI is Mimicing the Human Brain –"But Several Orders of Magnitude Faster and More Efficiently

China Creates a Laser of Mind-Boggling Power –"Could Rip Space Asunder, Breaking the Vacuum"

"Stop Saying That Dinosaurs Went Extinct. They Didn't"

 

 

 

 

"The Galaxy" in Your Inbox, Free, Daily