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Previous Moons Of Earth Have Collided To Form The Moon: Study

Moons
Newer theory of formation of Moon. (Image courtesy: Google)

For quite many years planetary scientists have chalked up over the moons origin by means of impact between the Earth and Mars or a larger sized body which is called Theia.

This theory suggests that about 4.5 billion years ago a newly-coalesced Earth was hit by another protoplanet.

This impact further pulverized in a sizable part of our young planet while sending the debris into the orbit where under its own gravity it accredited for making our moon. Study which was published on 9th January in Nature Geo-science is calling this under a question while proposing several impacts of smaller bodies instead of a single huge one.

Simulation: Four stages of the collision between the moon and a companion moon. (Image Courtesy: Google)
Simulation: Four stages of the collision between the moon and a companion moon. (Image courtesy: Google)

Method of Formation of Moon: Study

Robin Canup who is a planetary scientist at Boulder’s Southwest Research Institute says, “We have all been focused on the idea of finding a single impact. The out-of-the-box thinking here is to relax that assumption, asking, Can we form the moon in little bits?”

She was not involved in the study, yet she herself proposed that moon formed when Earth collided with another protoplanet which was nearly of the same size. Earth-Moon system is like a local oddball.

Relative size of the Earth’s Moon is quite huge as compared to the moons of other giant planets Jupiter, Saturn, Uranus and Neptune. None of these Moon’s are more than a few thousandths the mass of the planets which they orbit. Two moons of Mars are even smaller – hardly more than big boulders.

Our moon is little more than quarter of the diameter of the Earth and is having about 1.2 % of the Earth’s mass. Pluto and it’s moon Charon are the only bodies which are remotely similar.

These newer team of Israeli researchers suggests that the Moon which we see every night is not the first Moon. It is rather the last among the series of Moon’s which orbited the Earth in past.

New Theory of Moon Formation of Earth:

Newly proposed theory by Prof. Hagai Perets of the Technion and Weizmann Institute Profs. Raluca Rufo and Oded Aharonson is running counter to the commonly held “giant impact” paradigm. They shows that Moon is a single object which was formed following a single giant collision which was between a small Mars-like planet and Ancient Earth.

Prof. Perets who is a co-author says, “Our model suggests that the ancient Earth once hosted a series of moons, each one formed from a different collision with the proto-Earth. It’s likely that such moonlets were later ejected, or collided with Earth or with each other to form bigger moons.”

For checking the conditions of formation of such mini-moons or moonlets researchers ran 800 simulations of impact with Earth. Newer model is consistent with the current understanding of Science of the formation of Earth.

Over its last stages of growth, it has experienced many giant impacts with other bodies. Each of these impacts has contributed more material to the protoEarth, until it reached its current size.

Prof. Perets adding to the same says, “We believe Earth had many previous moon’s. a previously formed moon could therefore already exist when another moon-forming giant impact occurs.”

Tidal forces from the Earth could cause Moons to slowly migrate outwards. Pre-existing moon would be slowly moving out by the time another moon forms. Yet their mutual gravitational attraction could eventually cause the moons to affect each other and further change their orbits.

Lead author Prof. Rufo says, “It’s likely that small moon’s formed through the process could cross orbits, collide and merge. A long series of such moon-moon collisions could gradually build-up a bigger moon the Moon we see today.”

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