Little was known about Neptune ,which was discovered in 1846, until
the Voyager 2 encounter in 1989. It has a similar composition to Uranus and
is close in mass to Uranus. Its thick atmosphere made of hydrogen, helium,
and some methane and ammonia, gives it a bluish color.
On August 25, 1989, the voyager discovered Neptune, but only after
traveling 12 years at an average velocity of 19 kilometers a second (about 42
miles an hour). The Voyager 2 observed Neptune almost continuously from
June to October 1989. This discovery though, gives us just about all the info
Astronomers have studied Neptune since September 23, 1846, when
Johann Gottfried Galle, of the Berlin Observatory, and Louis d'Arrest, an
astronomy student, discovered the eighth planet on the basis of mathmatical
predictions by Urbain Jean Joseph Le Verrier. Scarcely after Galle and
d'Arrest first saw Neptune, British astonomer William Lassell spotted a moon
orbiting the planet and named it Triton (Which is explained in greater detail
later in the report).
In 1949 astonomer Gerard Kuiper discovered Nereid, the second
largest moon of Neptune. Nereid is only about 340 kilometers (210 miles) in
diameter and is so far from Neptune that it requires 360 days to make one
In 1981, a star would pass behind Neptune so that observers could
measure the starlight and how it changed as it passed through the upper layer
of Neptune's atmosphere. But the star's light flashed on and off before
Neptune passed in front of it. Astronomers concluded that some material
orbits Neptune, and was responsible for occasional blockage of the star's
NEPTUNE FACTS AND FIGURES
Neptune is the eighth planet from the sun and the fourth largest by
diameter. Neptune is smaller in diameter but larger in mass than Uranus.
orbit: 4,504,000,000 km (or 30.06 Astronomical Units) from the sun.
diameter: 49,528 km through the equator
mass: 1.0247e26 kg
In Roman Mythology Neptune (Greek: Poseidon) was the god of the sea.
Because Pluto's orbit is so eccentric, it sometimes crosses the orbit of
Neptune. Since 1979 Neptue has been the most distant planet from the sun
but Pluto will be the most distant in 1999.
Neptune's blue color is a result of the absorption of red light by
methane in the atmosphere.