MoonsOfUranus

Introduction
In addition to its rings, Uranus has 27 known moons. Some of these are large enough to have been seen from Earth with telescopes, while others were not discovered until the space probe [|Voyager 2] passed by in 1986. Uranus' axis is tilted nearly 90º so the rings and moon orbits are at right angles compared to its path around the Sun.



False colour image of Uranus taken with Palomar Observatory's 200-inch (5-meter) Hale Telescope and processed by Don Banfield. The rings are the red bits. //Image credit [|Palomar Skies].//

Categories of moons
The moons of Uranus are generally discussed in three categories: Inner, Large and Irregular.

__Inner Moons__

The inner moons are located in the same region close to the planet that is inhabited by the rings. The rings are probably the result of earlier moon collisions. As these moons are close to the planet their orbital periods (time taken to circle the planet) are very short. As well as this, their proximity to each other means that their gravity tends to affect each other as they orbit - this is called perturbing. The end result of these two factors is that the inner moons' orbits are chaotic and further crashes are likely.

__Large Moons__

Size comparison of moons to Uranus. Puck, Miranda, Ariel, Umbriel, Titania and Oberon. //Image credit //

The Large Moon category includes moons with a radius of 234km (Miranda) to 789km (Titania). These are the moons that are massive enough to have enough gravity to pull themselves into a spheroid (ball shape). They are about half ice and half rock.

__Irregular Moons__

Irregular moons are objects that have been captured into orbits after a planet has formed - as a result their orbits are eccentric, inclined to the planet's rotation and even retrograde to the host planet motion. Uranus' irregular moons were probably objects originally orbiting the sun but got caught up in Uranus' gravity sometime after it formed. They are ostly smallish, and certainly not massive enough to be squashed into spheres

Table of Moons - in order of distance from Uranus

 * Name || Distance from Uranus (1000 km) || Radius (km) || Notes ||
 * Cordelia || 49.77 || 40 || Inner ||
 * Ophelia || 53.79 || 21 || Inner ||
 * Bianca || 59.17 || 27 || Inner ||
 * Cressida || 61.78 || 40 || Inner ||
 * Desdemona || 62.68 || 32 || Inner ||
 * Juliet || 64.35 || 47 || Inner ||
 * Portia || 66.09 || 68 || Inner ||
 * Rosalind || 69.94 || 36 || Inner ||
 * Cupid || 74.8 || 12 || Inner ||
 * Belinda || 75.26 || 40 || Inner ||
 * S/1986 U10 || 76.4 || 40 || Inner ||
 * Puck || 86.01 || 81 || Inner ||
 * Mab || 97.7 || 16 || Inner ||
 * Miranda || 129.39 || 234 || Large ||
 * Ariel || 191.02 || 578 || Large ||
 * Umbriel || 266.30 || 585 || Large ||
 * Titania || 435.91 || 789 || Large ||
 * Oberon || 583.52 || 762 || Large ||
 * S/2001 U3 || 4280 || 6 || Irregular ||
 * Caliban || 7230 || 48 || Irregular ||
 * Stephano || 8002 || 10 || Irregular ||
 * Trinculo || 8571 || 5 || Irregular ||
 * Sycorax || 12 179 || 95 || Irregular ||
 * Margaret || 14 345 || 6 || Irregular ||
 * Prospero || 16 418 || 15 || Irregular ||
 * Setebos || 17 459 || 15 || Irregular ||
 * S/2001 U2 || 21 000 || 6 || Irregular ||