About how fast is an asteroid going when it hits a planet?

1 Answer
Dec 12, 2015

Probably rather variable, but of magnitude similar to #50,000# meters per second.

Explanation:

I think it would be quite variable depending on the circumstances, but similar in order of magnitude to the speed with which the Earth orbits the sun.

Let's do a few rough calculations:

The Earth is roughly #9.3xx10^7# miles from the sun

So the length of the Earth's roughly circular path around the Sun is about #2 pi# times this, say #5.84xx10^8# miles.

The Earth travels this path in about #365# days, so the miles per day is about #(5.84xx10^8) / 365 = 1.6xx10^6# miles per day.

Divide by #24# to get miles per hour: #(1.6 xx 10^6) / 24 ~~ 67,000# miles per hour

To get meters per second multiply by #1609.344/3600# to get about #30,000# meters per second.

Compare this with the speed at which comet Shoemaker-Levy collided with Jupiter, which is estimated at #60,000# meters per second. So it seems we're in the right ballpark.