This model assumes, therefore, that the second moon—and any other bodies—existed for all that time at gravitationally stable points, locked in synchronicity with the larger moon in orbit around Earth. At some point, the smaller moon would no longer be in a stable point, setting up the slow-speed merger.
Within million years, this gravitational jostling caused the cosmically slow splat that would have left Earth with the single moon we see today. A pair of NASA spacecraft launched last September 10 could help planetary scientists evaluate the scenario. Damond Benningfield is a freelance science writer and radio producer in Austin, Texas.
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Giant-impact hypothesis
Comment on this Story. For typical terrestrial planets with a mass of 0. The inclination of the resulting moon's orbit is random, but this tilt affects the subsequent dynamic evolution of the system.
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For example, some orbits may cause the moon to spiral back into the planet. Likewise, the proximity of the planet to the star will also affect the orbital evolution. The net effect is that it is more likely for impact-generated moons to survive when they orbit more distant terrestrial planets and are aligned with the planetary orbit. In , evidence was presented that suggests that the collision may have occurred later than the accepted value of 4. It has been suggested that other significant objects may have been created by the impact, which could have remained in orbit between the Earth and Moon, stuck in Lagrangian points.
Such objects may have stayed within the Earth—Moon system for as long as million years, until the gravitational tugs of other planets destabilized the system enough to free the objects. The giant-impact hypothesis fails to properly explain the similar composition of Earth and the Moon.
The second-moon theory.
Especially, the indistinguishable relation of oxygen isotopes cannot be explained by the classical form of this hypothesis. According to research on the subject that is based on new simulations at the University of Bern by physicist Andreas Reufer and his colleagues, Theia collided directly with Earth instead of barely swiping it.
The collision speed may have been higher than originally assumed, and this higher velocity may have totally destroyed Theia. Other mechanisms that have been suggested at various times for the Moon's origin are that the Moon was spun off from the Earth's molten surface by centrifugal force ; [9] that it was formed elsewhere and was subsequently captured by the Earth's gravitational field; [54] or that the Earth and the Moon formed at the same time and place from the same accretion disk. None of these hypotheses can account for the high angular momentum of the Earth-Moon system.
Another hypothesis attributes the formation of the Moon to the impact of a large asteroid with the Earth much later than previously thought, creating the satellite primarily from debris from Earth. In this hypothesis, the formation of the Moon occurs 60— million years after the formation of the Solar System.
Previously, the age of the Moon had been thought to be 4. The shared metal vapor bridge would have allowed material from the Earth and proto-Moon to exchange and equilibrate into a more common composition. Yet another hypothesis proposes that the Moon and the Earth have formed together instead of separately like the giant-impact hypothesis suggests. The new model, developed by Robin M.
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Canup , suggests that the Moon and the Earth have formed as a part of a massive collision of two planetary bodies, each larger than Mars, which then re-collided to form what we now call Earth. After the recollision, Earth was surrounded by a disk of material, which accreted to form the Moon. This hypothesis could explain facts that others do not. From Wikipedia, the free encyclopedia.
For other uses, see Big Splash disambiguation. Origin of the Moon.
NEW The Big Splat, or How Our Moon Came to Be by Dana Mackenzie | eBay
Moon — Oceanus Procellarum "Ocean of Storms". Ancient rift valleys — context. Ancient rift valleys — closeup artist's concept.
Astronomy portal Space portal Moon portal. The New York Times. Earth and Planetary Science Letters. Archived from the original PDF on Abstracts of the Lunar and Planetary Science Conference. Retrieved 7 July April , "Simulations of a late lunar-forming impact", Icarus , 2: Annual Review of Earth and Planetary Sciences. Retrieved 7 June Journal of Geophysical Research. Geochimica et Cosmochimica Acta. Lunar and Planetary Science.
Origin of the Earth and Moon Conference. A Violent Natural History. Add to Basket Add to Wishlist. Description of this Book This science history relates one of the great breakthroughs in local astronomy - the evolution of a successful theory of the moon's genesis that is little known outside of the scientific community.
A The Mail on Sunday, 30 March A New Scientist, 7 June A most useful and interesting book. For everyone with even the slightest interest in astronomyA A M2 Best Books, 14 July Besides telling an interesting tale well and elucidating how science progresses, Mackenzie's book emphasizes the fact that impacts have been the primary creative and destructive process throughout the history of the Solar System.