A protoplanet called Theia crashed into Earth 4.5 billion years ago.
A remnant of a protoplanet may be hiding inside Earth : Read more
A remnant of a protoplanet may be hiding inside Earth : Read more
What does that mean. Sorry I’m new to this site
hi there! -please be more specific in your questionWhat does that mean. Sorry I’m new to this site
The 1963 book is Sutton, F., Wolf, D. D. authors, The Moon, The How and Why Wonder Book of the Moon, by Wonder Books, Inc. Much is discussed on pages 4-6 on the origin of the Moon theories and pages 14-15 covering the changes in the Earth-Moon system over time.I suggest u could try to quote your reference?heh
-if that is your inclination to how you intuit it,
I would not mind, although to concur, I am willing to read ur post a few more times heh
I think it's really hard to be sure how our local bodies were placed
Yes, that comes from the grandfather of all Moon models that count as being scientific. This was from George Darwin (son of Charles). The outward increase in distance means that, if we rewind the clock, the Moon would have started with a ~5-hour rotating Earth, per his model.My observation. Interesting, this 1963 book on pages 14-15 discusses the slowing of earth's rotation and lengthening of the day and the moon slowly expanding its orbit and moving away from earth due to tides. "…as a result our days are becoming longer, at the rate of about 1/1,000th of a second a century…These changes due to tidal friction have been going on for billions of years, just as they are still going on. The earth-day, which was originally less than five hours, has lengthened to 24 hours. And the moon-month, which was originally the same length as the earth-day, has increased to about four weeks."
Of course it will be challenging to go back billions of years and produce hard evidence of what really happened. The early models didn't have the challenge of explaining things like isotope ratios.I find it interesting to review past origin theories on the Moon and compare with the present view, giant impact with Theia. In terms of the length of day billions of years ago and the lunar month (about 24 hours in the 1963 book), not much has changed with the giant impact using Theia. Demonstrating Theia is a real body that hit the proto-earth (other than in computer models) is a work in progress it seems. If I ask about the Moon so close to Earth billions of years ago and what evidence there is, that is another story
Nice little article but many other simulations have been done as well.Helio's post #16 favors isotope ratios and a Two Moon model. Other giant impact model reports sometimes provide more details. Here is an example.
Supercomputer simulations could unlock mystery of Moon's formation, https://www.sciencedaily.com/releases/2020/12/201204110254.htm, December 2020.
Yes, and this is probably always the case. All physics, I expect, begin with taking a stab at initial conditions. If the results are promising, begin tweaking those initial conditions and the modeling itself.My observation, more transparency is needed, this report shows some more details clearly, other than assumptions about initial isotope ratios for example. Different sizes and spin rates can alter much in the simulations and the outcomes of giant impacts. This model reported in December 2020, features a proto-earth with a 3 hour day after the giant impact so the 5 hour day from 1963 is still in the ball park and no giant impact was used
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My observation. As computer models become more detailed in the giant impact simulations, more and more special initial conditions arise that seem needed to make everything work
I think this rate is fast enough to fling out debris from Earth with no impact.I note in the arXiv paper link, https://arxiv.org/pdf/1805.00019.pdf, the proto-earth has a rotation period less than 1.5 hours for the length of day (as well as different angles of impact in the report).
Yes, those are important, and more parameters as well. It's been said for this modeling that it is surprising how hard it is to do simulations on "dirt".My observation. Initial proto-earth mass and rotation period is important, also Theia mass and spin rate, velocity and impact angle as well as where Theia first formed in the solar system, and later, hit the proto-earth.
Yeah. But there is other evidence that our young solar system was behaving like a pin-ball machine. Jupiter and Saturn moved in and out, wreaking havoc from these two, not to mention other migrations.Thus, how long was Theia a proto-planet in orbit around the Sun before hitting the proto-earth? If for example Theia had a stable orbit around the Sun for millions or even hundreds of millions of revolutions, we should still see Theia in the solar system today (perhaps).
The very fast post-impact rotation rate would be needed to account for migration of the likely proto-Moon's close orbital distance after we rewind the clock from now till then. The high rotation rate would have enough tidal effects, IMO, to help begin that migration, thus minimizing the likelihood of instability bringing it crashing back down onto Earth. I'm not qualified, however, to address this complicated behavior of tidal stresses and a multitude of blob-like bodies in odd orbits due to an impact.My observation. Some initial conditions like the proto-earth rotation rate before Theia impact used in the computer simulations, verification seems difficult to show the early Earth (proto-earth) ever had such a short length of day or a Moon with a very short lunar month, 24 hour period or less apart from the inputs used in the computer simulations.