From the moon's reference, the Earth orbits around it, traveling 2 × π × distance_moon_earth per orbit. Divide this by 27.3 days (sidereal orbital period) to ge

From the moon's reference, the Earth orbits around it, traveling 2 × π × distance_moon_earth per orbit. Divide this by 27.3 days (sidereal orbital period) to get the Earth's speed. Multiply by 1/250th of a second. And we find this is, again, much less than 4 miles. Using GNU units: $ units "2 * pi * moondist / (27.3 day) * (second / 250)" Definition: 4.0958765 m which is only 0.0025450597 miles.