Shadow Speed

A little arithmetic:

The diameter of the moon: 2,159 miles.

It takes 14 days to go from a new moon to a full moon.

There are 1209600 seconds in 14 days.
[14 days x 24 hours x 60 minutes x 60 seconds = 1209600 seconds]

There are 11,399,520 feet in 2,159 miles.
[2,159 miles * 5,280 feet per miles = 11,399,520 feet]

11,399,520 feet / 1209600 seconds = 9.424 feet per second.
Or 6.42 miles per hour.

This is the speed at which the shadow of the moon travels across its surface.

Which means if you were on the surface of the moon, you could keep jog along with the shadow, maybe even use it as a pace setter.

It also explains why the moon is only ever truly, completely full for an instant. The next full moon, for example, is the “Hunter’s Moon” on October 16, at 12:23 a.m.

If you have a good telescope, you could, if you wanted, photograph, over the course of three hours, the shadow traversing 19.27 miles.

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