(mysterious music)
- [Narrator] Along the dark edges
of the Solar System, it floats.
Anchored by a star but
barely graced by its warmth,
this traveler drifts alone
as deceptively calm and
elusive as the deep blue sea.
Neptune is the eighth planet from the Sun.
At about 30 times the distance
between our star and the Earth,
or 30 astronomical units,
Neptune is the most distant
planet in our Solar System.
This distance creates the longest orbit
of the eight worlds, about 165 years,
with the seasons lasting little
over 40 Earth years each.
Being so far away from the
heat and light of the Sun,
Neptune is cold, dark, and icy.
At its heart is a solid core
about 1.5 times the size of Earth.
Making up about 45% of the planet's mass,
the core is made of water
ice and silicate rock.
The rest of the planet is believed to be
a hot pressurized ocean of
water, methane, and ammonia ices
surrounded by a layer of clouds.
These clouds, predominantly
made of hydrogen and helium,
include traces of methane,
which give this ocean
world its rich blue color.
While the clouds create a
cool, calm veneer from afar,
up close, they are whipped around
by the most severe weather
in the Solar System.
Winds on the planet reach speeds
of over 1,200 miles per hour,
nearly five times faster
than the strongest
winds recorded on Earth.
In fact, the winds are so powerful
that they break the sound barrier.
Drifting high above this windy ice giant
is a quiet ecosystem of
rings and satellites.
Six rings encircle the planet,
with some containing ring arcs,
or clusters of dust particles in a ring.
Also revolving around the
planet are 14 known moons,
with the largest called Triton.
Named after the son of
the ancient Greek sea god,
Triton has ice volcanoes
and may even contain
a subsurface ocean.
Much is left to be
discovered about Neptune,
its rings and its moons.
Only one spacecraft, Voyager 2,
has visited these cosmic bodies,
but future missions to
this mysterious icy world
would have even more stories to tell.
