Space report on Neptune


            In this report I shall be investigating Neptune, the eighth planet from the sun.  First, I  shall be  studying the planet's discovery.  Next I shall be investigating Neptune's composition and figures. Thirdly I shall be covering Neptune's weather.  Fourth, I shall investigate the moons.  Fifth I shall discuss the rings. Lastly, I shall study the mythological origins of the names of Neptune and its moons. I hope you enjoy my report.


       Neptune was discovered 1846, in a large number of places.  It was first believed to exist, when astronomers looking at Uranus noticed that there was a bit of imbalance, that could only be caused by the gravity of another great celestial body pulling on it.  In 1845, the first astronomical theorist to work on the problem was a young British man named Adams, who accurately predicted where the planet would be  found in the night sky.  However he failed to find support for his discovery, and could persuade no experimentalists to look where his predictions showed for a new planet.  A year later, a French theorist of some repute named LeVerrier, took up the project.  He found where the planet should be, and published a paper about it, containing his measurements for the planet's position in the sky.  The measurements were almost exactly the same as those of Adams.  The experimentalists who took up the project after reading LeVerrierís paper were a team of Germans called Galle and deArrest.  They found a new disk like object in the sky where LeVerrier had predicted it to be.  The discovery of Neptune is credited to Adams and LeVerrier for they accurately predicted the position of Neptune.   Most all other discoveries that had anything to do with Neptune were made by the Voyager II Space Probe, the only space craft ever to reach Neptune.  Most everything that the report has to say about discoveries say ìDiscovered by Voyager II in 1989î

Composition and figures

            Neptune, is the eighth and sometimes the ninth planet from the sun. It is sometimes the ninth due to the eccentricity of the orbit of Pluto, which crosses that of Neptune at several places.  In relation to Uranus, it is smaller around, but composed of heavier material.  Its orbit is 4, 504,000,000 kilometers from the sun.  The diameter at the equator is 49,532 kilometers.  It weighs 1.0247 e 26 kilograms, which translated out of scientific notation is 102,470,000,000,000,000,000,000,000 kilograms.   Neptune's day (one complete rotation) is: 16 hours, and one year (one complete rotation around the sun) is 165 earth days.
 Neptune , has a composition rather similar to its neighbor Uranus, the seventh planet from the sun.  It has a rocky core, about the size of earth, that is covered with frozen water, helium, and hydrogen. That is surrounded by thick, dark clouds of Hydrogen Sulfide.  The inner atmosphere of Neptune is probably at its solid state.  Hydrogen sulfide is also a major component of skunk juice.  The outer atmosphere is a good number of clouds composed of Methane, Helium, and Hydrogen.  These are probably in their liquid form.  Neptune  also has a pretty good number of small white clouds, that go around the planet aimlessly. Neptune has vaguely similar basic structure to that of the other gas planets.  However, the particulars are  all unique to the planet.

This is a picture of the scooter.  The most pronounced of the irregular clouds.



           Neptune has particularly turbulent weather.  It has very powerful winds, that blow at an average speed of 960 kilometers per hour.   The greatest speed these winds have reached is 2000 kilometers per hour.  It has a large number of rather violent storms.  The most pronounced of which is (or was) the Great Dark Spot.  It was discovered in 1989 by Voyager II.  This particular storm goes around the planet at a speed of 1,120 kilometers.  Voyager II also found another storm of the same sort, in the southern Hemisphere.  However, when the Hubbell Space Telescope observed Neptune in 1994, it found no evidence of the Great Dark Spot.  It did find a new storm in the northern Hemisphere.  Most scientists think it has either dispersed or is masked by other aspects of the atmosphere.  There is also a major irregular white cloud, that goes around the planet once every 16 hours.  This cloud is known as ìThe Scooterî.  The observations, that Voyager II  made, compared with those of the Hubbell Space Telescope show that Neptune's weather changes rather rapidly.  Neptune's atmospheric conditions, are rather similar to that of the other giant gas planets. I also have my own theory, about the Great Dark Spot.  It is that the spot is a great and short lived vortex in the upper atmosphere, showing the darker lower atmosphere. It probably takes place due to variations in the magnetic field of Neptune which is very strong but has thin places for some very strange reasons.  The Great Dark Spot probably disappeared because of a fluctuation in the magnetic field.

This is a picture of the Great Dark spot, discovered by voyager II, and found gone by the Hubbell Space Telescope in 1994.



           Neptune has eight  moons, and all but two were discovered by the Voyager II fly-by in 1989.  The largest moon, Triton, has a large number of interesting traits.  But the basic information comes first.  Triton orbits 354,760 km. from the center of Neptune.  It is 2,700 kilometers around at the equator, and weighs 2.14 e 22 kilograms.  That figure translated from Scientific notation, is  21,400,000,000,000,000,000,000 kilometers.  It was discovered by a man named Lassal in 1846, in fact only a few weeks after Galle and DeArrest proved that Neptune existed.  Triton has a very interesting attribute, that it orbits Neptune, contrary to the direction Neptune orbits the sun.  This means, that it is moving slightly closer to Neptune with every orbit it makes.  This will either result in a collision with Neptune, or Triton breaking into little pieces. The only other moons that orbit this way, are a number of Jupiter and Saturn's smaller moons.  Triton is the only major moon that  orbits in this fashion.  All of the other interesting things about Triton were discovered by Voyager II.    Triton  has a very minor atmosphere that  is composed of nitrogen, and methane.  It also has a very large polar ice cap, that covers most of the This cap is composed of frozen nitrogen and methane.  It probably exists because Triton's surface temperature is  -235 degrees  C.  This is as cold as the surface of Pluto.  At that extreme cold, all the gasses on the surface will freeze solid.  The most interesting of all Triton's interesting features are the ìIce Volcanoesî.  These volcanoes erupt a mixture of frozen methane nitrogen, and very cold dust.  One of the main reasons they were discovered is that one was erupting when Voyager II passed by. The plume it made was 8 kilometers high, and spread for 150 kilometers down wind.  This also makes Triton one of  the only volcanic bodies in the solar system.  It shares this title with Venus, Earth, Mars, and Io ( one of Jupiter's moons).    One of the open ended questions about this small celestial body, is what force powers these volcanoes.  Next by size, comes the moon Proteus.


This is a picture of Triton the largest moon of neptune.  To see more a detailed description of this moon see text above.

Proteus  is the second moon of Neptune, by size.  It is  117,600 kilometers away from Neptune, and an average diameter of 418 kilometers. That is derived from the measurements of 436x416x402 kilometers.  It was discovered by Voyager II in 1989.  It was not found earlier due to the fact that it is dark and very close to a very bright planet.  It  is heavily covered with craters, showing no signs of any  geologic activity whatsoever.  This moon is irregularly shaped as well. It  is probably as big as an irregular body can get, without its gravity pulling itself into a perfect sphere.
 The next moon is Neried.  It was discovered by a ground based  observation in 1949 by the famous astronomer Kuiper. (The Kuiper Belt is named after him.) It orbits at an average distance of 5,513,400 kilometers away from Neptune.  It has a diameter of 340 kilometers.  Neried has the most eccentric orbit of any satellite in the solar system.  It varies from 9,623,200 kilometers, to 1,350,600.  The figure 5,513,400 kilometers, is obviously the median between the greatest and the lowest distance. The nature of the orbit probably means that the moon is a captured asteroid or Kuiper Belt item.  Next on the list  comes Larrisa, which the honor of discovery is disputed between ground based observation by Harold Rightsma, or Voyager II.  Both saw it in 1989.  It is 73,600 kilometers away from Neptune, and has a diameter of 193 kilometers.  It has a surface, much like that of Proteus with many craters and nothing else.  The next, is Galatea, which orbits 73,600 kilometers away from Neptune, and has a diameter of 158 kilometers.  Next is Despina, with  a diameter of 148 kilometers, and a distance from Neptune, of 52,600 kilometers.  Thalassa comes after Despina with a distance of 50,000 kilometers away from Neptune, and a diameter of 80 kilometers.  The last moon is  Naiad, with a diameter of 58 kilometers and a distance from Neptune of 48,200 kilometers.  All these moons were discovered by Voyager II in 1989.  All of Neptune's moons except for Triton, are almost unknown.
Name of Moon
Date of Discovery 
Distance From Neptune
2.14 e 22 kg.
354,760 km.
2,700 km.
117,600 km.
418 km.
5,513,400 km.
340 km.
73,600 km.
193 km.
73,600 km. 
158 km.
50,000 km.
80 km.
48,200 km.
58 km.


         Neptune, has four rings, all of which, are faint but present, like the rings of Jupiter and Uranus.  These rings are unique because they have bright patches.  From ground- based observation, it looked like Neptune had  small arcs for rings.  It was Voyager II that discovered that they are complete rings.  All four rings are named after discoverers of the planet or the moons.  The outermost or main ring, is called Adams, with bright spots called Liberty, Equality, and Fraternity.  This ring is 62,930 kilometers from Neptune, and less than 50 kilometers wide.  The next ring scientifically called the Plateau Ring is called Lassal and Arago, which is 53,200 kilometers away from Neptune and 5,800 kilometers wide.  Next comes the inner ring, which is called LeVerrier.  It is also 53,200 kilometers away from Neptune, but is only 15 kilometers wide.  Last is the Diffuse ring, called Galle.  It is 41,900 kilometers away from Neptune, and is 15 kilometers wide.

Classical mythology, connected to Neptune, and its moons

            Neptune, is the Roman god of the sea, earthquakes, and horses.  His parents are Saturn, the  highly celebrated god of agriculture, and Saturn's sister and wife ops, the goddess of wealth.  His Greek counterpart is Poseidon. Both versions of the god have two brothers, Jupiter (Zeus), and Pluto (Hades).  Neptune had one son, by the sea nymph Amphrite, whose name is Triton.   Triton  is half fish and half man.  The origins of the second moon of the planet Neptune is that Proteus is known as the ìOld Man of the Seaî.  He changes shapes  and can take any shape he wants to.  He is also a Seer, knows everything you need to know.  However he is very grumpy and choosy about who he gives good advice to.  He is very similar to  Nereus, son of Gaia and Pontus, the husband of Doris, daughter of Oceanus and Thethys.  They are also Sea Nymphs or creatures.  The pair are the parents of the 50 beautiful sisters, the Nerieds.  (One of the more notable of the Nerieds was the mother of Achilles, hero of the Trojan War, who was killed with an arrow in the heel by Paris.)  Next is Larrisa, who is the daughter of Pelasgus son of son of Triopas, son of Argus son of Zeus brother of Poseidon, and Niobe, daughter of Phroneus the first man, who was created by Zeus.  Next comes Galatea, who is one of the Nerieds, who lived near Sicily and was loved by Cyclops Polyphemus.  Next is Despina, who is the daughter of Poseidon and Demeter, goddess of the harvest and mother of Persephone, the symbol of spring.  The penultimate figure mentioned here is Thalassa, the Greek word for sea.  She is the daughter of Aether, god of light, and Hemera, goddess of day.  Aether, is son of Erebus who is darkness and Nyx who is night.  Nyx is also the daughter of Chaos, sister of Erebus, and Hemera.  Last comes Naiads, who are nymphs, and the guardians of all freshwater bodies. The most important of which are lakes, streams, pools, ponds, rivers, and fountain


             In this report I investigated Neptune, the eighth planet from the sun.  First, I studied  some general information about the planet.  Next I studied about  Neptuneís composition. Thirdly I studied the important parts about Neptune's weather.  Fourth, I  investigated the moons.  Fifth I covered the rings. Lastly, I investigated the mythological origins of the names of Neptune and its moons. I hope you enjoyed my report.


Arrnet, Bill
Fradin, Dennis B. Neptune.  Children's Press ®.  Chicago Illinois,©1990.
Panada, Carlos ©1997

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