Re: [tuning] Digest Number 1053

Hi Paul,

Just seen that the ref I found:
http://www.ucl.ac.uk/geolsci/edu/students/planet/student/work/io.htm
says that the angular velocity of Io is continually decreasing, so
I got it the wrong way round.

Looks as if the system as a whole is gaining energy rather than losing it.

Jupiter's bulge powers it by continually tugging at Io, and so making Io
gain energy, which means, go into a slightly higher and slower orbit.

Io then tugs on Europa, and Europa on Ganymede.

Hope I've got it right now... (I remember it was a bit kind of counter-intuitive
somehow).

Same thing is happening with our Moon and the earth, - the moon
is gaining energy, and its orbit is getting slightly slower, so the month is
getting longer, and at same time the earth's day is getting longer, so
earth's rotation is losing energy.

Slow orbit = higher energy, slow rotation of a planet = lower energy.

The Earth's tug on the Moon, instead of speeding it up, slows
it down! (and also slows down the earth's rotation).

Sorry to have got it the wrong way round, should have checked it
first.

Robert