All four Galilean moons stand out because of the swiftness of their motion, compared to the Moon. They are all also large enough to fully eclipse the Sun.
Jupiter's small inner moons appear only as star-like points except Amalthea, which can occasionally appear as large as Callisto. However, they would all be brighter than any star. The outer moons would be invisible except for Himalia, which would appear as a dim, star-like point to the naked eye only under favorable circumstances.
None of Jupiter's moons have more than traces of atmosphere, so their skies are black or very nearly so. For an observer on one of the moons, the most prominent feature of the sky by far would be Jupiter.
Because the inner moons of Jupiter are in synchronous rotation around Jupiter, the planet always appears in nearly the same spot in their skies. Observers on the sides of the Galilean satellites facing away from the planet would never see Jupiter, for instance.
From the moons of Jupiter, solar eclipses caused by the Galilean satellites would be spectacular, because an observer would see the circular shadow of the eclipsing moon travel across Jupiter's face.
The sky in the upper reaches of Saturn's atmosphere is blue, but the predominant color of its cloud decks suggests that it may be yellowish further down. The rings of Saturn are almost certainly visible from the upper reaches of its atmosphere. The rings are so thin that from a position on Saturn's equator, they would be almost invisible. However, from anywhere else on the planet, they could be seen as a spectacular arc stretching across half the celestial hemisphere.
Saturn's moons would not look particularly impressive in its sky, as most are fairly small, and the largest are a long way from the planet. Even Titan, the largest moon of Saturn, appears only half the size of Earth's moon. In fact, Titan is the dimmest of Saturn's large moons due to its great distance and dimness; Mimas, Enceladus, Tethys, Dione, and Rhea are all brighter. Most of the inner moons would appear as bright, star-like points (with the exception of Janus, although most would shine brighter than any star. None of the outer moons would be visible except Phoebe which would be very dim.
Since the inner moons of Saturn are all in synchronous rotation, the planet always appears in the same spot in their skies. Observers on the sides of those satellites facing away from the planet would never see Saturn. In the skies of Saturn's inner moons, Saturn is an enormous object.
Saturn's rings would not be prominent from most of the moons. This is because the rings, though wide, are not very thick. The rings are edge-on and practically invisible from the inner moons. From the outer moons, starting with Iapetus, a more oblique view of the rings would be available, although the greater distance would make Saturn appear smaller in the sky; from Phoebe, the largest of Saturn's irregular moons, Saturn would appear only as big as the full Moon does from Earth. The best view of the rings may be from the inner moon Mimas, which is fairly near the rings. The co-orbitals Epimetheus and Janus would also get a good view. Tethys gets the next best view; Iapetus gets a good view of the rings and is more than any of the outer moons can claim.
Titan is the only moon in the Solar System to have a thick atmosphere. The Titanean sky is a light tangerine color. However, an astronaut standing on the surface of Titan would see a hazy brownish/dark orange color. As a consequence of its greater distance from the Sun and the thickness of its atmosphere, the surface of Titan receives only about of the sunlight Earth does – daytime on Titan is thus only as bright as twilight on the Earth. It seems likely that Saturn is permanently invisible behind orange smog, and even the Sun would be only a lighter patch in the haze, barely illuminating the surface of ice and methane lakes. However, in the upper atmosphere, the sky would have a blue color and Saturn would be visible. With its thick atmosphere and methane rain, Titan is the only celestial body other than Earth upon which rainbows on the surface could form. However, given the extreme thickness of the atmosphere in visible light, the vast majority of the rainbow would be in the infrared.
Seen from Enceladus, Saturn would have a visible diameter sixty times more than the Moon visible from Earth. Moreover, since Enceladus rotates synchronously with its orbital period and therefore keeps one face pointed toward Saturn, the planet never moves in the sky of Enceladus and cannot be seen from the far side of the satellite.
Saturn's rings would be almost invisible, but their shadow on Saturn's disk would be clearly distinguishable. Like our own Moon from Earth, Saturn itself would show regular phases. From Enceladus, the Sun would have a diameter of only one-ninth that of the Moon as seen from Earth.
An observer located on Enceladus could also observe Mimas (the biggest satellite located inside Enceladus's orbit) transit in front of Saturn every 72 hours, on average. Its apparent size would be about the same size as the Moon seen from Earth. Pallene and Methone would appear nearly star-like. Tethys, visible from Enceladus's anti-Saturnian side, would reach a maximum apparent size, about twice that of the Moon as seen from the Earth.
Judging by the color of its atmosphere, the sky of Uranus is probably a light blue. It is unlikely that the planet's rings can be seen from its surface, as they are very thin and dark.
None of Uranus's moons would appear as large as a full moon on Earth from the surface of Uranus, but the large number of them would present an interesting sight for observers hovering above the cloud tops. Unlike on Jupiter and Saturn, many of the inner moons can be seen as disks rather than star-like points; the moons Portia and Juliet can appear around the size of Miranda at times, and a number of other inner moons appear larger than Oberon. The outer irregular moons would not be visible to the naked eye.
The low light levels at such a great distance from the sun ensure that the moons appear very dim; the brightest, Ariel, would shine more than 100 times dimmer than the moon as seen from Earth. Meanwhile, the outer large moon Oberon would be only as bright as Venus despite its proximity.
Judging by the color of its atmosphere, the sky of Neptune is probably an azure or sky blue, similar to Uranus'. As in the case of Uranus, it is unlikely that the planet's rings can be seen from its surface, as they are very thin and dark.
Aside from the Sun, the most notable object in Neptune's sky is its large moon Triton, which would appear slightly smaller than a full Moon on Earth. It moves more swiftly than our Moon. The smaller moon Proteus would show a disk about half the size of the full Moon. An alignment of the inner moons would likely produce a spectacular sight. Neptune's large outer satellite, Nereid, is not large enough to appear as a disk from Neptune, and is not noticeable in the sky. The other irregular outer moons would not be visible to the naked eye.
As with Uranus, the low light levels cause the major moons to appear very dim.
Triton, Neptune's largest moon, has an atmosphere, but it is so thin that its sky is still black, possibly with some pale haze at the horizon. Because Triton orbits with synchronous rotation, Neptune always appears in the same position in its sky. As Neptune orbits the Sun, Triton's polar regions take turns facing the Sun for 82 years at a stretch, resulting in radical seasonal changes as one pole, then the other, moves into the sunlight.
Neptune itself with a maximum brightness would be about that of the full moon on Earth. Due to its eccentric orbit, Nereid would vary considerably in brightness; its disk would be far too small to see with the naked eye. Proteus would also be difficult to resolve but, at its closest, would rival Canopus.