Artist's conception of the Sun's path in the summer sky of a major moon of Uranus which shares Uranus's axial tilt. All major moons comprise approximately equal amounts rock and ice, except Miranda, which is made primarily of ice. For instance, Titania was shown to possess no atmosphere at a pressure larger than 10—20 nanobar.
The path of the Sun in the local sky over the course of a local day during Uranus's and its major moons' summer solstice is quite different from that seen on most other Solar System worlds. The major moons have almost exactly the same rotational axial tilt as Uranus's their axes are parallel to that of Uranus. Template:Efn Near the equator, it would be seen nearly due north or due south depending on the season. Irregular moons of Uranus. The X axis is labeled in Gm million km and in the fraction of the Hill sphere 's radius.
The eccentricity is represented by the yellow segments extending from the pericentre to the apocentre with the inclination represented on the Y axis. As of Uranus is known to have nine irregular moons, which orbit it at a distance much greater than that of Oberon, the furthest of the large moons.
All the irregular moons are probably captured objects that were trapped by Uranus soon after its formation. The moons above the X axis are prograde , those beneath are retrograde.
The radius of the Uranus's Hill sphere is approximately 73 million km. Uranus's irregular moons range in size from — km Sycorax to about 20 km Trinculo. The lifetime of moons in the instability region is from 10 million to a billion years. Margaret is the only known irregular prograde moon of Uranus, and it currently has the most eccentric orbit of any moon in the Solar System, though Neptune's moon Nereid has a higher mean eccentricity. As of , Margaret's eccentricity is 0.
The Uranian moons are listed here by orbital period, from shortest to longest. Moons massive enough for their surfaces to have collapsed into a spheroid are highlighted in light blue and bolded. Irregular moons with retrograde orbits are shown in dark grey. Margaret, the only known irregular moon of Uranus with a prograde orbit, is shown in light grey. Template:Moons of Uranus. Template:Solar System moons compact. Template:Solar System navmap.
Space Shuttle. Explore Wikis Community Central. Register Don't have an account? Moons of Uranus. Edit source History Talk 0. From left to right: Puck , Miranda , Ariel , Umbriel , Titania , and Oberon Uranus , the seventh planet of the Solar System , has 27 known moons , all of which are named after characters from the works of William Shakespeare and Alexander Pope.
See also: Name conflicts with minor planets. See also: Inner moon and Rings of Uranus. See also: Irregular moon. Gerard Kuiper James L. Elliot William Herschel William Lassell. Voyager 2 flyby. The Solar System. In , another three moons were discovered: one was discovered while comparing images from Voyager 2 and two more were discovered by astronomers using the Canada-France-Hawaii Telescope at Mauna Kea. As of , 27 moons are known to orbit Uranus. Uranus and its five major moons are depicted in this montage of images acquired by the Voyager 2 spacecraft during its January flyby of the planet.
Miranda is the smallest of the five major satellites of Uranus, measuring just kilometers miles in diameter. Voyager 2 passed between Miranda and Uranus during , and returned this color composite of the moon. The carved dark streaks on the surface of this icy moon turned out to be ridges and valleys in higher resolution images. This high resolution image of Miranda was taken from a distance of 31, kilometers 19, miles , and shows a cratered surface broken by cliffs up to 20 kilometers 12 miles high.
Such fractures and grooves in the satellite's surface indicate a complex geologic history. Perhaps long ago, Miranda was broken apart by a catastrophic impact, but then the pieces pulled back together gravitationally, but in a mixed up order.
The grooved coronae would have then formed as the heavier, rocky parts of the moon descended to the interior and the more buoyant, ice-rich parts rose to the surface. Tidal forces from Uranus would have repeatedly flexed and squeezed Miranda, causing enough heat for the icy material of the moon to move easily.
Rising intrusions of warm ice called diapirs would have pushed up on the surface of Miranda, causing the grooved terrain that is seen. It is possible that a similar mechanism is responsible for the coronae on Venus, except that Venus has rising diapirs of warm rock, not ice, that create the oval, crown- like surface features. Learn more about Saturn and the rings. In addition to moons, Uranus also has rings—13 of them.
This sounds like a lot, but the rings are very thin and dark, with some wide separations. These rings were accidentally discovered in This is called an occultation study. In this style of study, one waits until the timing is just right, so that when looking from Earth, the planet to be studied passes in front of a faraway, fixed star.
This causes the star to appear fainter. But more importantly, the atmosphere absorbs certain frequencies of light from that star based on what the atmosphere is composed of. The surprising thing that happened at Uranus was that even before it reached the star, the star disappeared and reappeared several times.
The same disappearing act happened in reverse order when the star emerged from the other side of Uranus. This symmetry meant that what was being seen were not individual moons, but instead, rings. This initial discovery found five rings, and soon more followed. The rings were eventually imaged by Voyager 2. Though it is not known what the rings are made of, they are likely a mixture of rock and ice.
They may have formed from collisions of previous moons surrounding the planet. Their narrowness suggests that either the rings are extremely young, like 1 million years, or they must have shepherd moons like seen at Saturn for some of its thin rings. Some shepherd moons have been discovered for Uranus. For example, the small moons Cordelia and Ophelia shepherd one of the rings.
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