The moon could have formed in just five hours after a colossal collision that rocked the early morning solar system 4.5 billion years ago, scientists suggest.
For decades, experts have believed that the moon was formed when a Mars-sized planet called Theia collided with a young Earth, blowing huge amounts of molten rock into space.
This material was thought to have gradually clumped together over the years to form our lunar satellite.
But a team from the Southwest Research Institute and the University of Arizona saying that there might be another possibility.
Using powerful computer simulations, the researchers found that in some scenarios, a largely intact moon emerged surprisingly quickly after the crash.
The deciding factor turned out to be the temperature.
“Depending on how hot the Earth and Theia are prior to impact, an impact could destroy Theia and produce this huge disk of debris that eventually forms the moon,” said Dr. Adeene Denton.
“But when I used the same parameters as the original impact modeling – down to the equal temperature structures in both bodies – an intact moon emerged within about five hours.”
The researchers found that in some scenarios, a largely intact moon emerged surprisingly quickly after the crash – in just five hours.
The team discovered that the geological properties of the colliding worlds play a crucial role in what happens after the impact.
Previous models treated the planets largely as fluid-like bodies and ignored the strength of their rocks.
When the scientists took into account the strength of planetary materials and their temperatures, they arrived at dramatically different results.
Hotter planets are weaker and easier to tear apart, they said.
However, cooler worlds are stronger and more likely to survive the impact in one piece.
‘Models have evolved to include material strength, something that is very important when studying collisions between smaller bodies such as asteroids or for my previous paper on the formation of the Pluto-Charon system,’ said Dr Denton.
‘We weren’t sure if it would make a difference to the moon or not.
‘When we did the simulations, we discovered that it actually does matter.’
When the scientists took into account the strength of planetary materials and their temperatures, they arrived at dramatically different results
The findings may help explain some of the moon’s unusual features, including the amount of volatile materials it contains
The findings, published in Astrophysical diary letterscould help solve one of the biggest mysteries in planetary science – right when the moon-forming impact occurred.
Researchers say the work may also help explain some of the moon’s puzzling features, including differences in its composition and the amount of volatile material it contains.
Dr. Robin Canup, who conducted an earlier study on the moon’s origins, said: ‘These surprising and exciting new results imply a potential link between the physical properties of the current moon, including perhaps its volatile contents, and the thermal state of Earth and Theia at the time of the giant impact.
“This could, in turn, help scientists better determine when the moon formed.”
The researchers said explaining the close composition of the Earth and the moon remains an open scientific question.
One possible explanation is that Theia and a young Earth formed from a common region of the protoplanetary disk: a pancake-like ring of dense gas and cosmic dust.
Mars, on the other hand, differs in composition from Earth and the moon, suggesting that it initially formed further away.
“Because Earth and Mars formed in the same area of the solar system, they are like siblings,” Dr Denton said. ‘The moon and the earth are like fraternal twins.’
Last monthan out-of-control SpaceX rocket crashed into the moon, leaving a visible crater.
The Falcon 9’s second stage crashed into the moon’s surface at a speed of 8,690 km/h.
Scientists believe the 4,500 kg, 12 meter long rocket would have had a force equivalent to 15,000 sticks of dynamite, or three tons of TNT.
A NASA satellite captured images showing the result of the impact: a crater 60 feet (18 meters) wide, surrounded by streaks of moon rock thrown up by the rocket’s impact.
