Genuine question, how do they figure stuff like this out? I don't understand the science behind it or even the logical approach for such an event even happening
Here's a sampling of some of the evidence that supports this, from Wikipedia:
The Moon's orbit has a similar orientation to Earth's rotation,[8] both of which are at a similar angle to the ecliptic plane of the Solar System.
The stable isotope ratios of lunar and terrestrial rock are identical, implying a common origin.[9]
The Earth–Moon system contains an anomalously high angular momentum, meaning the momentum contained in Earth's rotation, the Moon's rotation and the Moon's orbit around Earth is significantly higher than those of the other terrestrial planets. A giant impact could supply this excess momentum.
Moon samples indicate that the Moon was once molten to a substantial, but unknown, depth. This may have required much more energy than predicted to have been available from the accretion of a celestial body of the Moon's size and mass. An extremely energetic process, such as a giant impact, could provide this energy.
The Moon has a relatively small iron core, which gives it a much lower density than Earth. Computer models of a giant impact of a Mars-sized body with Earth indicate the impactor's core would likely penetrate deep into Earth and fuse with its own core. If this occurred, it would leave the Moon, which was formed from coalesced ejectae of lighter crustal and mantle fragments that went far enough beyond the Roche limit and thus were not pulled back by Earth's gravity to re-fuse with Earth, with less remaining metallic iron than other planetary bodies.
The Moon is depleted in volatile substances compared to Earth. Vaporizing at comparably lower temperatures, they could be lost in a high-energy event, with the Moon's smaller gravity unable to recapture them while Earth did.
There is evidence in other star systems of similar collisions, resulting in debris discs.
Giant collisions are consistent with the leading theory of the formation of the Solar System.
Depending on your point of view, maybe none of these are a smoking gun. But it's an educated guess that explains a lot of little odd things. And then you can run simulations like the one pictured above and see that with the right initial conditions for the impact, the results are plausible.
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u/Universe_XoX 9h ago
Genuine question, how do they figure stuff like this out? I don't understand the science behind it or even the logical approach for such an event even happening