The ISS team has officially announced the discovery of a new moon, 7.5 km across, orbiting within the Keeler Gap. They have released two new images and a movie related to this announcement.

Discovery of the Wavemaker
http://ciclops.lpl.arizona.edu/view.php?id=1071

Wavemaker Moon
http://ciclops.lpl.arizona.edu/view.php?id=1074

I have this combined in a post on my blog as well:
http://volcanopele.blogspot.com/2005/05/mo...p-moon-aka.html

So what does this bring the total number of moons around Saturn? I remember when I was a kid there was 12 around Jupiter and 9 around Saturn, then, Voyager(s) put Saturn in the lead, then, Galileo gave the lead back to Jupiter...where do we stand?

Eric P / MizarKey

Hi all,

Interesting structures could be found especially in the movie - there are some fine dust (boulders) flowing in the Keeler Gap like curtains in the wind.

The Wavemaker moonlet in the high-res image looks not round - thus its gravity field is not uniform and produce more turbulence in my thoughts.

Hopefully Cassini could study this and the Encke-Pan connection more in future passes.
For studies of boulders in this regions I suspect encounter distances at minimum 10000km and lower - a risky business near the rings, but possible in the extented misson ? who knows ?

Roby72

The figure is now 44 known for Saturn. (Cassini has seen three other small objects near the F Ring which, however, it has not yet succeeded in re-observing -- they may just be temporary ring clumps.) The figure for Jupiter at the moment is, I believe, 63 (vs. 27 for Uranus and 13 for Neptune). The things are getting as annoyingly omnipresent as asteroids.

Yes, a little bit annoying, especially considering that most of the outher small satellites are, probably, captured asteroids... To me, is more and more evident that a convenient, universal lower limit should be established on the size/mass of an object in order to avoid to include also rings material in the definition of "moon"!

The grand total is now 47:

31 before the Cassini mission
3 confirmed satellites (Methone, Pallene, and Polydeuces) discovered by Cassini last year
12 satellites discovered last year and annournced last week by Jewitt et al.
and now S/ 2005 S 1

This brings us to 47.

[/quote]

The figure is now 44 known for Saturn. (Cassini has seen three other small objects near the F Ring which, however, it has not yet succeeded in re-observing -- they may just be temporary ring clumps.) The figure for Jupiter at the moment is, I believe, 63 (vs. 27 for Uranus and 13 for Neptune). The things are getting as annoyingly omnipresent as asteroids.

[/quote]
The grand total is now 47:

31 before the Cassini mission
3 confirmed satellites (Methone, Pallene, and Polydeuces) discovered by Cassini last year
12 satellites discovered last year and annournced last week by Jewitt et al.
and now S/ 2005 S 1

This brings us to 47.

[/quote]

I should have done this before asking...simple google search...

Planetary Society has this to say (Saturn = 49) Moon Count

Nasa sidesteps the question by answering Your question, a very good one, by the way, is one that has no single correct answer - it is one that is being actively researched now!

Ever changing numbers...I'm sure Uranus and Neptune have their share of teeny tiny moons too.

Eric P / MizarKey

The Planetary Society don't proofread so good:

"Eleven are tiny bodies orbit among or just outside the main ring system. These may just be big clumps of ring stuff. In fact, the identification of three of them as moons is not yet certain; they could have just been transient clumps in the rings, long-lived enough for Cassini to spot them in a sequence of ring images, but dissipating later. The nine ring-related moons are: Pan, Atlas, S/2004 S3, S/2004 S4, S/2004 S6, Prometheus, Pandora, Janus, Epimetheus, Methone, and Pallene."

That "nine" is, I presume, actually the figure if you don't count the three Doubtful Clumps but DO add the newly discovered Keeler Gap moon. So, assuming that the Society's count of Saturn's swarm of outer captured moons is correct (and not yet counting the Doubtful Clumps), Saturn's total firm count is 47.

Looks like there's two new pictures of the wavemaker moon, both taken just before the Rhea images on August 1. They claim to be targeted at "SATURN-RINGS" -- guess "S/2005 S1" isn't a valid option for the TARGET attribute?

N00037450
N00037451

And hey, Bruce, next time you notice a typo in one of my stories, please email me, I won't be insulted!

Emily

If you count those possible ring clumps you still get nine moons -- Methone and Pallene orbit between Mimas and Enceladus, so they are not ring-related. They don't belong to that list.

New S/ 2005 S1 image: PIA07584: Keeler Moon and Waves

http://photojournal.jpl.nasa.gov/catalog/PIA07584

I hereby nominate the name "Mentos" for this moon...Mentos, the Wavemaker! Think of the corporate sponsorship opportunities...

I hereby nominate 'Oasis Leasure Centre, Swindon" - as they've got a great wavemaker in their pool.

Doug

Well heck, Mentos even sounds like the name of a mythological person/creature/thing!

The wavemaker's name is Daphnis. According to the IAU, " Shepherd, pipes player, and pastoral poet in Greek mythology. Son of Hermes, brother of Pan, and decendant of the Titans. Discovered orbiting in the Keeler gap in Saturn's A ring."

Here's a new great view ...

- http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=82561

Daphnis on September 09, 2006 (50.5 KB):

Are there any developed theories on how ring gap moons form? Or arrive at their current orbit? Are they developed in-situ planetessimal-like? Or perhaps just larger remnant fragments of the moon which disintegrated and formed the larger ring system?

I'm curious about the brighter areas bordering the scalloped edges of the gap before and behind the moonlet. Do they represent areas of greater ring-particle density? I'm having a hard time imagining what this actually would look like if you were within the rings.

I'm thinking it has something to do with gravitational resonances from the moons. A small resonance would cause a local thickening of a ring, which would cause a very small moonlet to form within the ring. The moonlet would then exert its own gravitation on the surrounding ring particles, causing the gaps we see.

Of course, that's an opinion from an admitted amateur...

-the other Doug

Perhaps. But I imagine that type of event could be modeled given the current orbits of the larger moons.

Does Daphnis look bigger (compared to the size of the ring gap) at PIA06237: Wavemaker Moon than at PIA07809: Daphnis At Work?

Are my eyes playing tricks on me because of different distances and viewing angles?

-- Kevin Heider

Looks like the field of view and degree of magnification is larger and lower, respectively, for the 2nd link.

Why does Daphnis cause ripples ahead and behind but on opposite sides of the rings. In Latest wavemaker image you've got waves on the lower left (inner) ring and on the upper right (outer) ring but not on the upper left inner ring or lower right outer ring. I get turned around in these images...is the orbit counterclockwise in this image, so the trailing wake is the inner disturbance?
Wouldn't Daphnis' gravity tug uniformly?
Does Daphnis have a synchronous rotation about Saturn?

May be because of a higher phase angle (less of its surface lit) in the second image.

Its all to do with differential motion.

The particles at the ring gap edges feel the greatest force due to gravitational interaction with Daphnis at the point of closest approach i.e. when they are at the same longitude as the satellite. Yes they are affected by Daphnis' (as well as by everything else in the Universe's) gravity all the time but the effects are neglible. Its only when they are at very near closest approach to Daphnis that there is any discernable effect.

Using the impulse approximation is a very good model for the interaction. The ring particles receive a 'kick' at their closest approach, there is an exchange of angular momentum and the ring particles' eccentricty increases. Its this increased eccentrcity that results in the observed sinusoidal edge waves that we see on the gap edges.

Now remember that the particles at the inner ring edge are orbiting 'faster' than Daphnis i.e. their angular velocity is higher. These particles approach Daphnis from 'behind', recieve a 'kick' while passing the satellite and then move away from Daphnis in the prograde (direct) direction. So on the inner gap edge you see the edge waves 'ahead' of Daphnis while the material 'behind' the satellite hasn't passed the satellite yet, hasn't receive a 'kick' so you don't see edge waves.

The material at the outer gap edge has a lower angular velocity so Daphnis 'catches up' with the ring particles from 'behind', the particles receive their 'kick' and then fall behind the faster satellite. At the outer gap edges you see the edge waves 'behind' the satellite since the particles 'ahead' of Daphnis haven't passed the satellite and haven't interacted with it yet.

Of course all particles at the gap edges 'pass' Daphnis many times over the course of time but the observations show that the edge waves soon damp out due to interaction between the ring particles themselves so effectively they have no memory of their previous encounter when they next interact with Daphnis.

In a nutshell (and not all that well explained :-) ) thats why you only see the waves 'ahead' of Daphnis on the inner gap edge and 'behind' on the outer gap edge. The inner edge wave is the 'leading' one and the outer 'trailing'. Currently the sunlit side of the rings is the south face so in the images we are looking at the rings from 'below' -- so the prograde orbital direction in the image you reference is clockwise. In textbooks diagrams of the orbits of objects in the Solar System are (almost) always shown as viewed from the north hence prograde being anti-clockwise.

I think that synchronous rotation is assumed -- there just aren't enough observations yet to be sure but its a good bet that it is.

pat