leading edge of moons?

In message . 204, Paul
Lawler writes
Jonathan Silverlight wrote
Paul Lawler writes
"Rick" wrote in :
"A.Gent" wrote in message
"Paul Lawler" wrote in message

Really? Which satellites (moons) in our solar system are not
tidally locked to their planets?

Hyperion + Saturn

Correct. Hyperion is locked in a 3:4 orbital resonance with Titan.

Wow... see what happens when you keep your eyes open... you learn things!

The day I stop learning things I'll be dead (which recalls the
uncomfortable CM Kornbluth line).
Does anyone even know if the outer moons of Jupiter and Uranus are
tidally locked? The Jovian moons are in retrograde orbits and are
supposed to be captured asteroids like Phobe, which isn't locked, for
instance.
Neptune's moon Nereid isn't locked, either.

Okay, now I'm confused. After much Googling, I was under the impression
that Hyperion was the only satellite (moon) in our solar system that is not
tidally locked.


Nope :-) A bit more searching took me to NASA's Solar System Exploration
page at http://solarsystem.nasa.gov/index.cfm, and looking round there
I was able to find that Elara (Jupiter VII) has a rotation period of 0.5
days, and Himalia (Jupiter VI) 0.4 days. I couldn't find the others, but
I'm willing to bet they are similar - tidal forces on all of them will
be tiny.

Thanks everyone for your answers.

This is all news to me.

For some unknown reason, I had just assumed that Luna's
orbital behavior was an aberration of our "special" Earth.
I guess we're not all that special... good!

Well, you know what they say about assumptions...

Is there some simple generalization that can be made
about moons... that, with the exceptions of x, y, and z
all moons (over X diameter) in the Solar system present
the same face (are tidally locked) to their planets?

heron

--
unDO email address
___
Nature, heron stone
to be commanded,
must be obeyed. http://home.comcast.net/~heronstone/

"heron stone" wrote in message ...
Thanks everyone for your answers.

This is all news to me.

For some unknown reason, I had just assumed that Luna's
orbital behavior was an aberration of our "special" Earth.
I guess we're not all that special... good!

Well, you know what they say about assumptions...

Is there some simple generalization that can be made
about moons... that, with the exceptions of x, y, and z
all moons (over X diameter) in the Solar system present
the same face (are tidally locked) to their planets?

Generally, planets and their major satellites are of the same
age, and moons have had equal (i.e. enough) time to tidally
lock to their planets. Time and rate of rotation are the main
factors here -- diameter has little to do with it. Hyperion is
considered either a relatively recent knock-off from another
moon, or a recently captured KBO.

Rick