Moons of Uranus objects: their geometrical albedo varies between 30 and 50%, whereas their Bond albedo is between 10 and 23%. Umbriel is the darkest moon and Ariel the brightest. The masses of the moons range from 6.7 kg (Miranda) to 3.5 kg (Titania). For comparison, the Moon has a mass of 7.5 kg. The major moons of Uranus are thought to have formed in the accretion disc, which existed around Uranus for some time after its formation or resulted from a large impact suffered by Uranus early in its history. All major moons comprise approximately equal amounts rock and ice, except Miranda,
Titania (moon) exists, it would have to be far thinner than that of Triton or Pluto. This upper limit is still several times higher than the maximum possible surface pressure of the carbon dioxide, meaning that the measurements place essentially no constraints on parameters of the atmosphere. The peculiar geometry of the Uranian system causes the moons' poles to receive more solar energy than their equatorial regions. Because the vapor pressure of CO is a steep function of temperature, this may lead to the accumulation of carbon dioxide in the low-latitude regions of Titania, where it can stably exist on high albedo