There is a movie coming about about the world ending, it's not the same tone as 2012, it's more of a romantic comedy.It's called "Seeking a friend for the end of the World". Anyway the trailer mentions that the asteroid coming towards earth is 70 miles wide. I was thinking that would obliterate the Earth. I mean obviously it will wipe out all life, but could an asteroid that massive cause the Earth to break into pieces. Assume the it's a spherical rock, 70 miles wide means a 35 mile wide radius. Our atmosphere is only 300-400 miles tall. I'm guessing that it would enter the atmosphere and make contact with the ground or ocean in an instant at that size. I would try to calculate the kinetic energy it would have, but seeing as though I took classical physics like 3 semesters ago I don't remember everything. I'm also pretty sure my book wouldn't have everything to needed to calculate the energy involved. I know this is just a hypothetical situation but I thought if anyone would have fun calculating some numbers about this, I would find them here.