OK, I am seeing how this all ties together. The polestar for Triton and the polestar for Nereid are, of course, different, and over longish periods of time their respective polestars change, just as ours on earth does. And the polestar for every particular object in the solar system (well, I bet Jupiter's Galilean satellites are all very close or the same) is different.

Is their a nice list of the polestars for all the solar system objects somewhere? I would be very interested in Neptune's and Iapetus' polestars.

This get back to me wondering some months ago if Iapetus' orbital plane about Saturn is rather more closely aligned with the ecliptic (BTW, is the ecliptic the ecliptic, or do we recognize Saturn as having one different from that we define from earth?) and whether or not that alignment to the ecliptic is expected to be stable over the age of the solar system.

Someone with Starry Night or Celestia could answer the pole star questions quickly. I don't have either on this computer.

Iapetus's inclination WRT the ecliptic is 14.72 deg, almost the same as its inclination WRT Saturn.

Thanks for the information regarding Iapetus. Interesting that currently, seasonal effects on Iaptus are significantly less pronounced than at Titan or Saturn.

Iapetus is weird in so many ways. A day that is ~80 earth days long, coupled with weak seasonal changes. Mars, earth, Pluto, Neptune, Triton all have greater variation in insolation during their respectve years. And can anybody think of an object other than Venus that rotates slower?

Is it just a coincidence, or do we infer possibly a similar effect 'relaxing' Iapetus' orbital plane towards the ecliptic as possibly has happened to earth's moon? Perhaps we might have a long term solar tidal effects doing this?

I looked into this last year; I can't give exact coordinates, but it turned out that most of the large objects in the Solar System share a general orientation, with a north celestial pole within the first big curve (starting from the head) in the constellation of Draco -- just about where the center of Earth's circle of precession is (the North Ecliptic Pole) and, coincidentally, the Cat's Eye Nebula. That includes the Sun, Venus, the Moon, and Jupiter. Jupiter's large moons share Jupiter's orientation. Ceres and Mercury's north pole is still within Draco, but closer to Xi Draconis, in the "head" of the dragon.

Mars' north celestial pole is about halfway between Deneb and Alderamin, at the edge of the constellation Cygnus. Neptune's is close to Delta Cygni.

Uranus' is in Orion, midway between Bellatrix and Aldebaran. Triton's is in Sagitta. Pluto's north pole is close to the boundary of Delphinus and Equuleus.

Saturn's north pole is actually close to Polaris, though not quite as close as Earth's. Iapetus' pole is a little further off, between Polaris and Beta Cephei. Titan and Saturn's other moons closer in share Saturn's orientation.

One thing to consider in more depth is the rate of polar precession for each object. I suspect that this is rather slow--if it exists at all-- for most planetary moons due to tidal lock effects, but probably a direct function of rotation period for the planets themselves (exception: Uranus' precession cycles must truly march to the beat of a different drummer... ) Come to that, Mercury & Venus must also be a bit different in this regard due to resonance effects, the latter apparently correlated to Earth(!)

Getting OT here for sure, but interesting.

EDIT: Does Hyperion's odd rotational state indicate relatively recent capture by Saturn, or can its behavior be explained by other influences? Doesn't seem like its polar orientation is fixed/periodic at all...

Creating a thread for some OT posts in another thread.

I appreciate breaking out a thread on this. Thanx!

The orientation of all these objects orbital planes relative to each other is fascinating. From little Neried being aligned rather closely to the ecliptic (and perhaps making it more approachable for study by a probe on it's way to Neptune/Triton) to Iapetus having perhaps an evolutionary tidal effect we may be able to study on our own moon. And then we have the pole position of Mercury to contemplate . . .

I think we are synergistically enabled by having good data sets on so many objects now that our knowledge of all objects is enhanced.

Back on Neptune, any future craft in orbit there, utilizing Triton for orbital modifications like Cassini and Galileo, will most likely spend several orbits in or near the plane of the ecliptic at some point in the mission. As we have seen at Saturn, backlighting of the target planet by the sun yields some scientifically invaluble (as well as beautiful) images. So now it is just a matter of timing in working out a flyby of Nereid. (assuming we didn't get our flyby on approach to Neptune)

Another possibility for orbiting Neptune is consideration of the Neptune/Triton mass ratio. It is already quite favorable for flying interesting orbital tours, perhaps it will help the trajectory designers at JPL to find an orbital tour that can start out prograde, and through repeated Triton flybys, the orientation of the orbit can be flipped 180 degrees (over a span of many orbits) and the craft can be brought into a retrograde orbit for the final phase of the mission. The utility of a retrograde orbit about Neptune for a Triton orbit/landing is evident . . .

On a linguistic side-note, as our terms "Arctic" and "Antarctic" refer to the orientation of the Earth's poles toward or away from the constellation of Ursa Minor (Ursus = Arktos = "bear"), they are inappropriate when used for planets which do not have the same orientation. For instance, on Mars, where the north pole points toward Cygnus, the correct terms would probably be "Ornithic" (from Ornis, the Greek name for the constellation Cygnus) and "Antornithic". On Venus, or Jupiter or its closer satellites, they would be "Draconic" and "Antidraconic", meaning pointing to or away from the constellation Draco.

Now that's a piece of trivia worth learning. Here's to Phoenix's Ornithic adventure!