What if you 'placed' the Chicxulub asteroid onto the Earth? We all know what sort of devastating impact an asteroid could have if it collided with the Earth.
But I'm curious to know what the effects would be if you removed the speed element from it, and were somehow able to casually 'place' a giant asteroid onto our planet?
I think I read somewhere that the Chicxulub asteroid was most likely around 9 miles long, and that the end of it would have extended beyond our atmosphere if it hit the Earth lengthways.
But would this have any effect if it was travelling at, say, 2mph? There would be nothing burning in the atmosphere or shockwaves etc.
Would it have any affect at all apart from squashing whatever was underneath?
If the answer is no... how about placing a moon-sized object onto the Earth?
An asteroid resting on Earth would be a mountain. Or, for smaller asteroids, a pile of gravel.
Mountains are limited in altitude by the strength of stone to resist compression: a too tall mountain would sink down as the base crumbled and spread out. The limit on Earth is about 10 km. Besides the strength issue mountains are also floating (&quot;isostasy&quot;) on the fluid but denser interior of Earth, so even if it doesn't fall apart it may sink down partially.
So the impactor would not hold together that well. A big ball of rock 10 km in diameter would first definitely sink down several kilometres into the crust, and almost definitely break. That means that something like $10^{15}$ kg will descend several kilometres, giving an energy $mgh \approx 10^{19}$ J (and there are estimates 100 times larger for the mass). That is &quot;just&quot; like a big hurricane, but will mostly be released as localized seismic energy and heating. The end result would be a massive pile that likely destabilizes the crust in the vicinity a lot: far less than an actual high velocity impact, but still a major disaster.
If you do the same with the moon you will break up the crust, boil off the oceans and wipe out all life on the planet.