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GENERAL INFORMATION:
Neptune is the eighth planet from
the sun and the fourth largest in diameter. It has a diameter of 30,500
miles. Along with Pluto, it is one of the only planets that cannot be
seen without a telescope. Neptune has eight moons and several rings.
Like Earth, Neptune is almost completely composed of water. It is often
referred to as one of the "Blue Planets." It is also one of
the windiest planets in the solar system. Like a typical gas planet,
Neptune has rapid winds in its bands and large storms or vortices. Its
winds are the fastest in the solar system, even reaching 2000 km/hour.
Neptune, along with Jupiter and Saturn, has an internal heat source,
radiating more than twice as much energy as it receives from the Sun.
Neptune travels around the sun in an elliptical orbit and revolves
around the sun every 165 years. It takes this long because Neptune is
2,798,800,000 miles away from the sun. As it makes its revolution, it
rotates on its axis. The axis is at a tilt of 30 degrees to the
perpendicular. Neptune makes one spin every 16 hours and 7 minutes.
Because Pluto's orbit is so eccentric, it sometimes crosses the orbit of
Neptune, making Neptune the most distant planet from the Sun for a few
years.
Neptune has been visited by only
one spacecraft, the Voyager 2 on August 25 1989. Most of our knowledge
of Neptune is from this single encounter as well as ground-based
observations. Neptune's magnetic field is oddly oriented and is
generated by motions of conductive material within its layers. The
magnetic field of Neptune is highly tilted at 47 degrees from the
rotation axis and offset at least 0.55 radii (about 13,500 kilometers or
8,500 miles) from the physical center. Neptune can be seen with
binoculars but a large telescope would be needed to see more than a tiny
disk.
When Neptune was discovered in
1846, astronomers named the planet after the Roman god of the deep sea.
Not only did they do this to keep the tradition of naming planets after
mythological figures, but also because of its position in 'deep' space.
This turned out to be the perfect name for Neptune when we saw its deep
blue color in photographs! The symbol for it is a stylized trident.
Neptune's largest moon, Triton, was named after the Greek god of the
sea, Poseidon's (Neptune's) Son.
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COMPOSITION:
Neptune is made up of hydrogen,
helium, water and minerals known as silicates. The internal atmosphere
consists of compressed gases. The first two thirds of Neptune is
composed of a mixture of molten rock, water, liquid ammonia and methane.
The outer third is a mixture of heated gases comprised of hydrogen,
helium, water and methane. Methane gives Neptune its blue cloud color.
It is covered by thick clouds.
Neptune has many clouds that circle rapidly. Winds blow these clouds up
to 700 miles an hour. The clouds furthest from Neptune are composed of
methane. The lower clouds are darker and are composed of hydrogen
sulfide.
Neptune has three basic weather
patterns. These are known as the Great Dark Spot, the Small Dark Spot,
and Scooter. The Great Dark Spot is a storm system almost as large as
Earth! It spins around once every 16 days. It is surrounded by frozen
methane clouds which condense over its edges. The Small Dark Spot has a
small cloud over its center. Between these two is Scooter, a triangular
white cloud lying deep in the atmosphere. Neptune's center is very hot
with a temperature of 7,000 degrees Celsius. The heat that Neptune
creates is greater than it receives by the sun.
Neptune also has rings. One of the
rings appears to be slightly twisted. Neptune's rings are very dark but
their composition is unknown. They have been named as well, the
outermost is Adams (which contains three prominent arcs named Liberty,
Equality and Fraternity), next is an unnamed ring co-orbital with
Galatea, then Leverrier (whose outer extensions are called Lassell and
Arago), and finally Galle.
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