Yahoo – AFP,
Mariëtte Le Roux, January 9, 2017
 |
| NASA/JPL-Caltech The theory used to be that the … Continued The post A new theory challenges everything astronomers thought they knew about how the Moon was created appeared first on Business Insider. |
Paris (AFP)
- The Moon, our planet's constant companion for some 4.5 billion years, may
have been forged by a rash of smaller bodies smashing into an embryonic Earth,
researchers said Monday.
Such a
bombardment birth would explain a major inconsistency in the prevailing
hypothesis that the Moon splintered off in a single, giant impact between Earth
and a Mars-sized celestial body.
In such a
scenario, scientists expect that about a fifth of the Moon's material would
have come from Earth and the rest from the impacting body.
Yet, the
makeup of the Earth and the Moon are near identical -- an improbability that
has long perplexed backers of the single-impact hypothesis.
"The
multiple impact scenario is a more 'natural' way of explaining the formation of
the Moon," said Raluca Rufu of the Weizmann Institute of Science in
Rehovot, who co-authored the new study published in the journal Nature
Geoscience.
Such
multiple hits would have excavated more Earth material than a single one, which
means the moonlets would more closely resemble our planet's composition, said
the study authors.
Rufu and a
team created nearly a thousand computer simulations of collisions between a
proto-Earth and embryonic planets called planetesimals, smaller than Mars.
Every
collision would have formed a disk of debris around the proto-Earth which
would, in turn, clump together to form a "moonlet", they found.
Moonlets
would eventually coalesce to form the Moon.
"In
the early stages of the Solar System, impacts were very abundant, therefore it
is more natural that several common impactors formed the Moon rather than one
special one," Rufu told AFP.
 |
Our Solar
System is thought to have formed 4,567 billion years ago, followed
by the Moon
about 100 million years later (AFP Photo/Daniel Leal-Olivas)
|
Discarded
theory revived
Our Solar
System is thought to have formed 4,567 billion years ago, followed by the Moon
about 100 million years later.
Numerous
"impactors" would have excavated more Earth material than a single
one, which means the moonlets would more closely resemble our planet's
composition, said the study authors.
About 20
such crashes would have been required to build the Moon, they concluded, while
conceding that further study is needed into the mechanics of Moon formation
from "moonlets".
The
giant-impact hypothesis was first proposed in the mid-1970s, followed in the
1980s with the first suggestions that several collisions may have given the
Earth its tide-creating satellite.
The latest
study has "revived the hitherto largely discarded scenario that a series
of smaller and more common impacts, rather than a single giant punch, formed
the Moon," Gareth Collins of Imperial College London wrote in a comment
carried by the journal.
"Building
the Moon in this way takes many millions of years, implying that the Moon's
formation overlapped with a considerable portion of Earth's growth," he
added.
Study crashes main Moon-formation theory https://t.co/APwYsbnAWr pic.twitter.com/bRoOCUnMFn— AFP news agency (@AFP) January 9, 2017
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Scientists date Moon at 4.470 billion years
Answer: No, but there used to be, and the pattern was set. You were originally a dual sun system. Dual sun systems are ripe for the development of life as you see it. Contrary to those who would wish to frighten you, this lost sun will never return.
Question (2003): Dear Kryon,
is there anything specific located at the second focal point (besides the sun)
that makes the Earth (and all the other planets) move elliptically instead of
in a plain, round circle around our single sun?
Answer: No, but there used to be, and the pattern was set. You were originally a dual sun system. Dual sun systems are ripe for the development of life as you see it. Contrary to those who would wish to frighten you, this lost sun will never return.
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