# Amazing number I

I discovered a truly amazing fact the other day, one I had not seen reproduced anywhere before.

The radius of the Earth is 6371km.

The distance to the Moon is 382,260km.

Divide one by the other and you get exactly 60. Not approximately, but exactly. To lots of decimal places.

When you do a seemingly random calculation like this, and you get an answer that is so exact and significant (after all, there are 60 seconds in a minute, 60 minutes in an hour, 60 is at the heart of our time keeping), then you just know this is no coincidence.

Even more amazing is that, if you use miles instead of kilometers, you get exactly the same result!

But it makes sense. You do see people attaching significance to calculations like this which are plainly nonsense, but both these figures are distances and we know that the Moon does orbit the Earth, so they could be connected in some way.

Now, you may want to ask a few questions about this. How do we know the distance to the Moon so accurately, and how do we know the radius of the Earth?

How far away is the Moon? Well, we can’t just string a tape measure from here to there… except we can, kind of.

The Apollo astronauts left basically large prisms on the Moon. Fire a laser beam at that and it reflects back exactly where it came from, do a few calculations involving the time it takes to go and return and the speed of light, and you have a very accurate distance.

You could do it yourself if you have a very powerful laser and a very accurate time keeping device.

There are many methods, actually.

How do we know the radius of the Earth? Well, we live here, we can measure the curvature, use pictures from space, wrap a tape measure around it and use 2πr… well, perhaps not that. But we have known the radius reasonably accurately for thousands of years.

But you may have more questions…

This entry was posted in Science. Bookmark the permalink.