why has the size of meteors...?

Question

...changed during the history of the solar system?
e.g. older craters on the moon are generally bigger than younger craters, why is this?

Answer 1

Quite right Matt - the larger chunks of rock spinning around our solar system were swept up first ( mainly by Jupiter). This is because the gravitational attraction will be greater on a larger mass, so they will tend to be dragged towards the planets first. So the remaining rocks in orbit will have a smaller average size than 1000s of years ago - so meteor impacts are less frequent than they were and are of a smaller size - that does not mean that there aren't large ones out there just ready to drop out of the sky at any moment take care - buy a big umbrella!!

Answer 2

I don't think the size has changed significantly, but the number of randomly orbiting objects naturally decreases over time as those in unstable or intersecting orbits either hit something or get flung out of orbit by a close encounter. As for the age/size distribution of lunar craters, it's just the natural layering process. You can see small young craters on top of larger old craters, but the older small craters get obliterated by the big ones. It's not that older craters are bigger, but that bigger craters last longer.

Cunny is wrong - while the gravitational force acting on a bigger rock is greater, it takes more force to move the rock, too. All objects in a gravitational field are accelerated at the same rate.

Answer 3

I hate to be rhetorical but if the big ones crashed into Earth first then why worry about another big one hitting the planet ?

I think that at the beginning when the solar system was a forming, big and small meteors crashed into the planet or moon. The smaller impacts were probably eroded over time due to volcanic activity.

Answer 4

Big Uns crash first