The Solar System and the Planet Earth 299
the planet appears to have parallel brown bands on a yellow background.
In addition, there is a giant red spot whose dimensions have been as large
as 48,000 kilometers by 13,000 kilometers. The giant red spot appears to
be floating on the surface of the planet. It is believed to be some kind of
storm or disturbance. Its exact nature is a mystery, however.
The planet does not have a clearly defined surface but rather the
interior of the planet and the atmosphere flow continuously into each
other like the Sun. The planet is composed primarily of hydrogen (71%
by mass) and helium (25% by mass) like the Sun with traces of ammonia
and methane. It is believed that Jupiter has a rocky core, which is
surrounded by the hydrogen and helium gas, which makes up the bulk of
the planet. The planet also has an atmosphere made up of hydrogen and
helium. The planet resembles the Sun in many ways and is believed to be
a star that was not massive enough to ignite itself. The temperature of the
surface is approximately 140 K. The planet has a strong magnetic field. It
emits synchrotron radiation from its radiation belt, which is considerably
more extensive than its terrestrial counterpart.
Jupiter has at least 67 moons. The four innermost satellites of Jupiter
are large objects with nearly circular orbits. The other satellites are small
and irregular objects and are, very likely, asteroids captured by the giant
planet. The planet also has a ring of cosmic dust like Saturn but not as
prominent.
Saturn
Saturn, the second largest planet, orbits the Sun once every 29.5 years at
a distance of 9.5 AU. Its mass is 95 times that of Earth. Saturn resembles
Jupiter in many ways. It displays the same band structure. It also rotates
on its axis once every 10 hours, which accounts for its oblate spheroid
shape. It is composed of basically the same material as Jupiter and even
has a rocky core, but is less dense and there is a smaller percentage of
helium. Saturn emits non-thermal radio waves like Jupiter.
Above the rocky core is thick liquid metallic hydrogen where the
distance between the protons is less than the Bohr radius of the hydrogen
atom. Above this layer is liquid hydrogen and helium over which a
gaseous atmosphere extends for 1000 km. The interior temperature of
Saturn is in places as high as 11,400 K like at its core. As a result of this
it radiates more than twice as much energy into space as it receives from
the Sun.