Moons of Uranus these five, Titania, is 1,578 km in diameter and the eighth-largest moon in the Solar System, and about one-twentieth the mass the Earth's Moon. The orbits of the regular moons are nearly coplanar with Uranus's equator, which is tilted 97.77° to its orbit. Uranus's irregular moons have elliptical and strongly inclined (mostly retrograde) orbits at large distances from the planet. William Herschel discovered the first two moons, Titania and Oberon, in 1787, and the other three ellipsoidal moons were discovered in 1851 by William Lassell (Ariel and Umbriel) and in 1948 by Gerard Kuiper (Miranda). These five have planetary mass,
A Beautiful Planet does not have a planetary magnetic field. Consequently, "its atmosphere was ripped away from the planet by the solar wind. If you could stand on Mars today, you would find a landscape of lifeless desolation; very cold, and very dry." One of the current challenges in maintaining Earth's planetary "life support system" is global warming. The film shows how Earth's warming climate is causing the Greenland ice sheet to melt, and drives the point home by showing the Jakobshavn Glacier calving an incredibly large number of icebergs in relatively rapid succession as the end of this flowing river of ice