Alien rock remains found not on but deep inside the Earth The remains of a giant ancient space rock that scientists believe collided with Earth billions of years may be hiding deep below Earth's surface, according to a research paper published in Nature on Wednesday. A team of geophysicists and astronomers, led by the California Institute of Technology (Caltech), point to two " …
We determine it on Earth via sensing of earthquakes, so you'd need to station a large network of sensors all around that other planet or moon. That's feasible for the Moon, and maybe someday Mars, but that's about it for any likely such investigations in the lifetime of most reading this. No chance of doing it for planets orbiting other stars until we are able to reach them with a probe, which is probably many lifetimes away if ever.
Nice animated gif showing the continents overlaying these structures https://upload.wikimedia.org/wikipedia/commons/2/29/LLSVP.gif (apparently mostly under africa and the mid pacific.)
Embedded in this wikiP page https://en.m.wikipedia.org/wiki/Large_low-shear-velocity_provinces/
I have always found this stuff (geosciences) fascinating.
I think it's very interesting learning about our planets history while we walk, and fly around, today wondering if aliens are visiting us.
We know our planet's history resulted in life and while there are a lot of possibilities of various forms of life on other planets in the universe, how much has happened to us that changed our planets life? Our past events have probably been very helpful, impacts on a planet with no water covering it have a very low chance of creating life and there's a lot of evidence that meteorites helps create life on our wet world after the moon appeared. And then much later the impact that eliminated dinosaurs helped life to recycle for us, and a more recent impact may have eliminated a massive ice age, extending life all over our planet outside the tropics.
Interesting thought that the Theia collision might have been even more significant in our history than previously understood. It could reduce the value of ne in the Drake Equation very significantly.
Of course, we have very little insight into any of those values - virtually the only data we have is that N >= 1.
I don't think so, plate tectonics seems to be a consequence of a molten core/mantle, and afaik the evidence is very strongly against life needing plate movement to flourish, though it's pretty obvious that the actual evolutionary paths that life on earth has followed would be very different without plate movements.
There are many convection movements in the mantle. How do these Theia's remnants stayed connected together and weren't mixed with Earth's mantle? Does that mean Theia is not soluble in Earth?
The more we know, the more we realize we are ignorant.
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