Planet Moon Orbit Moon
rotation orbit direction fate
(days) (days)
Earth & Moon 1.00 27.32 Prograde Spiral outward and be stolen by the sun
Mars & Phobos 1.025 .319 Prograde Spiral inward and crash into Mars
Mars & Deimos 1.026 1.26 Prograde Spiral outward
Jupiter & Io .414 1.77 Prograde Spiral outward
Jupiter & Callisto .414 16.7 Prograde Spiral outward
Saturn & Pan .440 .575 Prograde Shepherd moon
Saturn & Titan .440 15.9 Prograde Spiral outward
Uranus & Cordelia .718 .335 Prograde Spiral inward and become shredded into a ring
Uranus & Puck .718 .762 Prograde Spiral outward
Neptune & Triton .671 5.88 Retrograde Spiral inward and become shredded into a ring
Pluto & Charon 6.39 6.39 Prograde Stable
All of these moons are tidally locked to their planets. None of the planets
are tidally locked to their moons except Pluto, which is tidally locked to
Charon.
The tidal stretching axis of the moon always points to the center of the planet.
If the planet is tidally locked to the moon, the planet's tidal stretching axis points
to the cneter of the moon.
If the planet is not tidally locked to the moon, the planet's stretching axis
is slightly offset from the center of the moon according to the table below.
In general,
Moon orbit Moon orbit / Moon Planet tidal axis
Planet rotation fate
Prograde < 1 Spiral inward Points behind of moon orbit
Prograde > 1 Spiral outward Points ahead of moon's orbit
Prograde Planet locked to moon Stable Points to the center of the moon
Retrograde any Spiral inward Points behind the moon's orbit
