[Izzy Dunne]

The asteroid crosses from one side of the Moon's orbit to the other in 31 hours.

The moon is about 235,000 miles from Earth.
That makes its orbit about 470,000 miles from one side to the other.
470,000 miles in 31 hours is 15,161 miles per hour !!!

That's what I call MOVIN' !!!

[Las Vegas Dave]

I would also add the approximately 60,000 mph (earth's rotation around the sun)to the 15,000 mph to get the direct hit speed of the collision, but if it hit at an angle, the direct hit speed would be less, but it still would be a disaster

[ngc6656]

The moon is about 235,000 miles from Earth. That makes its orbit about 470,000 miles from one side to the other. 470,000 miles in 31 hours is 15,161 miles per hour !!!

That amounts to 4.2 miles per second. If it is that slow in its orbit around the Sun while in Earth's vicinity it should not be here, it should have already spiraled into the Sun. The writer of "31 hours to cross the Moon's orbit" (paraphrased) didn't provide us enough information. I suspect Earth is catching up to the asteroid as they independently travel around the Sun and that the asteroid's velocity in space is on the order of 14 miles per second.