The Greatest Mysteries of Uranus Uranus’ tilt essentially has
the planet orbiting the Sun on its side, the axis of its spin is
nearly pointing at the Sun. CREDIT: NASA and Erich Karkoschka,
U. of Arizona Each week, Life's Little Mysteries presents The
Greatest Mysteries of the Cosmos, starting with our solar
system. More than a billion and a half miles away from Earth
looms a huge, cyan-colored world pegged with a perilous name:
Uranus. (For the record, modern astronomers tend to pronounce
the planet's name as "YUR-inn-us" rather than the giggle-
inducing alternative.) Along with Neptune, Uranus is considered
an "ice giant," a class of planets distinct from the much-larger
gas giants Jupiter and Saturn. Although hydrogen and helium gas
make up much of Uranus, significant quantities of water, methane
and ammonia "ices" give the planet a different color and
chemistry. Size-wise, Uranus' radius is four times that of
Earth's, and about 16 Earths could fit inside the ice giant's
sphere. Humankind hasn't had a close