I am not amazed, just frustrated, every time I watch a sci-fi movie (that is pretending to be a serious sci-fi work and not fantasy) where the plots points include items that are so obviously not part of reality, as in basic physics.

So often in off hand remarks, gravity is used as something that is obvious… yet in these movies it appears gravity is not obvious.

Example: meteor moving to hit ground, jets intercept and blow it up with a sidewinder missile.

Why that really doesn’t work: if a solid (stone, metal) meteor has a mass of say a thousand metric tons, blowing up a sidewinder on its surface still results in a thousand metric tons coming down at the same terminal velocity, but now simply in a few chunks.

Example: the moon cracks up because its hit by an asteroid.

Why that doesn’t really work: the reason the moon is a sphere in the first place is that its own mass is pulling on itself in three dimensions. Just whacking it a bit with an asteroid doesn’t change that fact. The moon is still just a mass sufficient to pull itself into a sphere. It won’t crack in two. Any asteroid which can shatter the moon has to be big enough that the kinetic energy involved will also melt the masses and they will end up into many small bits and pieces.

These are not hard things.