GabyDespite the fact that the Moon is Earth’s closest neighbor, scientists have been struggling with the mystery of its origin for centuries.
In the 1980s, astronomers suggested that this natural satellite of our planet was formed as a result of a catastrophic collision with the protoplanet Theia at the beginning of history. Lands However, a recent study by a team from the University of Pennsylvania has shown that the so-called collision theory may be incorrect.
Did the Earth capture the Moon?
Instead, researchers claim that the Earth could have “simply” captured the Moon as it passed by, during a process known as binary exchange capture.
this radical theory suggests that the Moon may have formed as part of a “terrestrial double system” – a pair of rocky objects orbiting each other. When they passed within Earth’s gravitational zone, Month one body was pulled into orbit, while the other was ejected into space.
The lead author of the study, Darren Williams, a professor of astronomy and astrophysics, noted: “No one knows for sure how the Moon was formed. For the past four decades, we had one theory about this. Now we have two.”
Why is the popular collision theory failing?
In 1984, astronomers gathered at a conference in Kona, Hawaii, to finally reach a consensus on how the Moon was formed. Using 363 kg of lunar material brought back by the missions NASA “Apollon,” scientists have discovered that the chemical composition of the Moon is similar to that of Earth, but not completely identical. Based on this, researchers concluded that the Moon likely formed from debris ejected during a collision between a celestial body and the young Earth.
This theory was popular because it aligns well with what we currently know about the chemical composition of the Moon. However, it does not explain all the details.
For example, Professor Williams and his co-author Michael Zugger noted that if the Moon had formed from a ring of debris slowly coalescing into a sphere, we would expect it to orbit above the equator. However, in reality, the Moon’s orbit is tilted away into a different plane (approximately seven degrees from the equatorial plane), the publication reported. Daily Mail .
A fresh attempt to explain the birth of the Moon.
To find an alternative explanation, astronomers considered a phenomenon known as binary exchange capture. According to this, Earth could have “stolen” a rocky body from a passing tandem and turned it into its satellite.
In support of this idea, Professor Williams cited the example of Triton, the largest moon of Neptune. Modern theories suggest that Triton was captured by Neptune from the Kuiper Belt, where it is believed that one in every ten objects is binary.
Like our Moon, Triton rotates at a significant tilt, deviating by 67 degrees from the planet’s equator. According to mathematical models, it is quite likely that the same could have happened with our Moon.
In an article published in The Planetary Science Journal, researchers calculated that Earth could have captured an object with a mass ranging from one to 10 percent of its total mass. The mass of the Moon is only 1.2 percent of Earth’s mass, which fits well within this range.
The only condition is that the double object would have to pass at a distance of only 128,750 km from Earth at a speed no greater than 10,800 km/h. Although this may seem incredibly fast, in the scale of Solar system such movement is similar to a leisurely stroll.
The problem is that even at such moderate speeds, at the moment of the Moon’s arrival, its orbit would have been highly elongated, like that of a comet around the Sun. However, researchers suggested that this orbit could have evolved over time under the influence of tidal forces.
This theory has a number of key advantages. For example, it explains the presence of certain chemical isotopes found on the Moon but not on Earth. At the same time, researchers acknowledge that their theory will be difficult to prove and that it is based on several controversial events that occurred simultaneously. However, Professor Williams assures that capture through binary exchange is a viable alternative to the standard collision theory and deserves further consideration.
