The moon was created from a collision in Earth’s distant past – but not how has traditionally been believed, according to a new study led by a group of scientists at Harvard University and the University of California, Davis.

The enormous impact from when a Mars-sized rock crashed into the earth more than four billion years ago created a donut-shaped astrophysical phenomenon they’re calling a synestia, as described today in the Journal of Geophysical Research: Planets.

The massive vaporized and liquefied mass gradually separated into the Earth and the moon over the aftermath of the impact – a marked difference that differs from the traditional theory developed over the last few decades, which proposes the moon spinning off from the intact Earth.

“This new work explains feature of the moon that are hard to resolve with current ideas,” said Sarah Stewart of UC Davis, one of the authors. “This is the first model that can match the pattern of the moon’s composition.”

The new theory holds that the impact vaporized about a tenth of the world’s mass, and everything else was liquefied. It bloomed out in a donut shape, according to the theory.

The vaporized rock gradually condenses, and then rains toward the center of the dynamic structure. What is to become grows, then gradually condenses and shrinks.

It is only after the moon’s creation that the whole rest of the synestia mass condenses, leaving a ball of spinning liquid rock that takes even longer to harden into the planet Earth.

In this scenario, the moon would be created in a few tens of years, and the Earth would take another 1,000 years to form.

The scientists say the physical evidence backs their theory. The Earth and moon share elements that have the same isotopic signatures – but the moon shows fewer volatile elements such as potassium sodium and copper which are found in abundance on Earth. The multiple of atmosphere of vapor, and the extreme temperatures, would explain the lack of volatiles on the moon, they contend.

Lock and Stewart first proposed the concept of synestias last May in the same journal.