Titania (moon) may have a subsurface ocean at the core–mantle boundary. The thickness of this ocean, if it exists, is up to and its temperature is around 190 K. However the present internal structure of Titania depends heavily on its thermal history, which is poorly known. Among Uranus's moons, Titania is intermediate in brightness between the dark Oberon and Umbriel and the bright Ariel and Miranda. Its surface shows a strong opposition surge: its reflectivity decreases from 35% at a phase angle of 0° (geometrical albedo) to 25% at an angle of about 1°. Titania has a relatively low Bond albedo of
Mars trilogy help them better adapt to the new worlds; to breathe thinner air (e.g. Russell), or to see better in the dimmer light of the outer planets. The books also speculate on the colonization of other planets and moons in the Solar System, and include descriptions of settlements or terraforming efforts on Callisto, Mercury, Titania, Miranda and Venus. Toward the end of the last novel, humans are taking sub-light colony ships to other stars, taking advantage of the longevity treatments to survive the trip to their destinations. A great portion of "Blue Mars" is concerned with the effects of extreme longevity