It's happening because of the conservation of angular momentum
between the earth and moon.

As the tides move lots of water around the earth's surface, the drag actually slows the rotation of the earth by a bit. Because of that, to conserve angular momentum, the distance between the orbiting bodies increases slightly.

It's the same effect (albeit in reverse) as seen when a skater does a pirouette and her rotational speed increases as she draws her arms in towards her.
( K2k6 has a proper job these days, Fri 15 Jan 2010, 14:13, 2 replies, latest was 16 years ago)

I was aware of the slowing effect of moon on earth
but not the other bit. interesting stuff
( Vipros. clever got me this far, then tricky got me in, Fri 15 Jan 2010, 14:15, Reply)

I liked it better when it was a mystery.

( crackhouseceilidhband Fuck off back to Mumsnet, Fri 15 Jan 2010, 14:15, Reply)

K2k6 ruins everything.

( thealternativefact, Fri 15 Jan 2010, 14:20, Reply)

Pah
You just can't cope with teh Science!
( K2k6 has a proper job these days, Fri 15 Jan 2010, 14:24, Reply)