Posted on 01/09/2017 9:59:14 AM PST by Red Badger
Currently, the leading theory of the creation of the Moon is that it formed from a giant impact between a very early Earth and another Mars-sized planet.
Yet new research from the Weizmann Institute of Science in Israel has put forward a theory that the Moon may have actually formed from a series of large impacts, rather than just one.
The study, published in the journal Nature Geoscience, explains why the Moon appears to be made mostly from Earth-like materials, rather than a mixture of our elements and those of another mystery planet.
Lead author Dr Raluca Rufu and her colleagues conducted some mathematical simulations of what it would look like if large planetary bodies collided with our Earth way back when it was newly formed around 4.5 billion years ago. In these tests, the impacts produced disks that shot off from Earth and the other body, but were mostly made up from Earth materials.
According to their results, it would take about 20 of these collisions to assemble the moon. Rufu told Business Insider that it is much more likely that the Moon formed from many smaller collisions, because it is a more organic process.
“The multiple impact scenario is a more ‘natural’ way of explaining the formation of the Moon,” Rufu said. “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.”
Also, Rufu said that the current theory doesn’t really explain why the Moon is so similar to rocks on Earth.
“If multiple of bodies contribute to the final Moon, their chemical signatures can even out, therefore the traces of the various impacts will be masked,” she said. “Also, higher velocity impactors can excavate more Earth material, hence the moonlets will resemble the Earth’s composition.”
The team suggest in their paper that moon-forming impacts between the early Earth — known as the proto-Earth — and other large bodies floating around were very common during the early days of the Solar System. Therefore, this series of events can probably be applied to other planets and moons.
“We see evidence of past impacts on all the terrestrial planets,” said Rufu. “This paper shows that moonlets can be commonly formed, therefore the lack of moons around Venus is an interesting follow up question of how planets can sometimes lose their moons.”
Proof of this new theory may lie in the heart of the Moon itself. If multiple impacts are the key, this implies that the Moon formed over many millions of years, rather than in a single massive crash. This would mean that the Earth and Moon’s interiors could be less mixed up, and may have preserved a record of the events.
Absolutely, Dave. Be my guest.
From Universe Today: “The volume of the Moon is 21.9 billion cubic km. Again, that sounds like a huge number, but the volume of the Earth is more like 1 trillion cubic kilometers. So the volume of the Moon is only 2% compared to the volume of the Earth. Finally, let’s take a look at mass. The mass of the Moon is 7.347 x 1022 kg. But the Earth is much more massive. The mass of the Earth is 5.97x 1024 kg. This means that the mass of the Moon is only 1.2% of the mass of the Earth.”
Actually, the density of the earth and the moon are within a factor of 2. Seems fairly close.
Yet our moon is a quarter of the size of Earth.
Sum Ting Wong.
Volume of the moon is 2% of volume of Earth. Using the 1/4th figure conflates “size” and volume.
Now you know how Copernicus and Galileo felt!................
From my photo hi-res look, that rectangle is in 3-D, i.e., there is something placed ON the picture. Looks similar to a SD card plastic container.
That's kinda the point.
How can the moon be only 2% the mass (not volume) of Earth, yet be a quarter the size, if it's solid?
If it's solid, shouldn't it be a quarter the mass of Earth? Logic says it should, unless it's made of something vastly lighter than our planet, or it's hollow.
Speaking of that, why did the NASA seismometer record a full hour of ground reverberation after the Apollo 11 L.E.M. crashed into it? Why did it record three hours of reverberations when they crash landed a second L.E.M. on a susequent mission?
“How can the moon be only 2% the mass (not volume) of Earth, yet be a quarter the size, if it’s solid?”
Basic physics. As a measurement of size goes up(say the diameter of the moon) the volume goes up by the cube of the diameter. Volume=4/3 * Pi * (Diameter/2)cubed So if you double the diameter of a sphere with a diameter of 2 inches to a diameter of four inches, you get the following change in volume.
Size (diameter) Volume (cubic inches)
2 in. 4.2 cubic inches
4 in. 33.51 cubic inches
So as the diameter of the sphere increases by a factor of 2, the volume goes up by a factor of 8.
Thanks for the mathematics lesson.
We still can’t account for the “ringing” of the moon, nor its enigmatic origins.
When we solve those mysteries, it’s going to flip everyone’s noodles.
Bow dare they try to undo “settled science!”
There are several indian legends that we once had two moons.
There’s also the weird account of a monk in England in the early medieval period, describing apparently an asteroid crashing into the moon, and the whole thing shimmied, wobbled and even sort of shimmered like a reflection on the water, implication being that it isn’t at all solid.
Amazing.
“We still can’t account for the “ringing” of the moon, nor its enigmatic origins.”
Yes. That’s interesting.
There it is!
Volume of Luna : Earth = about 1 : 51, which if their compositions were the same would place the moon’s mass as just short of 2% of Earth’s. The moon’s composition seems to be mostly materials like the Earth’s mantle and crust, without so much the iron and nickel core. So a mass of about 1.2% seems reasonable.
And this too:
“The Moon’s size and distance contribute to a wonderful coincidence for those of us who live here on Earth. The Moon is about 400 times smaller than the Sun, but it also just happens to be about 400 times closer. The result is that from Earth, they appear to be the same size. And when its orbit around Earth takes the Moon directly between Earth and the Sun, the Moon blocks our view of the Sun in what we call a solar eclipse. This is just the same as when you use your thumb to block your view of something that is both much larger and much farther away.”
http://spaceplace.nasa.gov/review/dr-marc-earth/moon-general.html
“Coincidence that sun and moon seem same size?”
“Bottom line: The sun’s diameter is about 400 times larger than that of the moon – and the sun is also about 400 times farther from Earth. So the sun and moon appear nearly the same size as seen from Earth. What are the odds?”
http://earthsky.org/space/coincidence-that-sun-and-moon-seem-same-size
Psalm 19:1-4 The heavens declare the glory of God, the dome of the sky speaks the work of his hands. Every day it utters speech, every night it reveals knowledge. Without speech, without a word, without their voices being heard, their line goes out through all the earth and their words to the end of the world.
I think that God, the Author of all science, put the sun and moon and earth (four variables - sun size, moon size, earth to moon distance and moon to sun distance) all in perfect order just as a faint glimpse of the order of the heavens. Something that has made man ponder things greater than himself - all the way from ancient man to us.
By the way - the U.S. will be getting a total eclipse of the sun on Aug. 21, 2017. My older teen daughters are excited for a road trip to see it. (My wife - not so much, so will enjoy the home alone for awhile!)
BTW - this eclipse will only be visible from land in the U.S. The last time that happened was 1776 or something!
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