Neptune is the eighth planet from the Sun, but becomes the ninth while Pluto's orbit comes inside its orbit. Neptune was the first planet to be discovered by mathematical calculations instead of viewing it by eye or through a telescope, although Galileo proposed a large bodily mass near Jupiter 233 years before its official discovery. It was also registered as a star by Lalande, a French astronomer in 1795. Neptune was officially discovered during and intensive search by many astronomers on September 24, 1846, by two German astronomers: Johann Galle and Heinrich d'Arrest. It was named by them after the god of the sea in classical mythology.
The average distance of Neptune's orbit from the sun is 2,800,000,000 miles (4,500,000,000 km). It takes Neptune 164.79 years to orbit the Sun. Oddly, because of this extensive orbit, Neptune has not completed one orbit around the sun since its discovery. The rotational axis of Neptune is at an angle of 29š. A "day" on Neptune takes 16 hours and 3 minutes. Neptune has a slightly smaller mass than Uranus, though its mass is 17.23 times Earth's mass. Neptune's density is 1.64 times that of water.
When viewed, Neptune appears bluish, with streaks of white clouds. Neptune appears blue because the red light is canceled out by the methane in its atmosphere. Storm systems, the size of Earth are blown around the planet at speeds that can reach 700 miles per hour. Thirty miles above the dense blue cloud there are cirrus-like clouds formed from frozen methane, that stretch thousands of miles long in ranks.
Because of its distance from the sun, Neptune generates its own energy. Neptune contains an internal heat source.This heat source is generated by internal heat that hurls frozen gases outward. This heat also causes the intense winds and great whirlwinds that occur in the clouds.
One of these great whirlwinds is the Great Dark Spot. It is the size of Earth and it can be seen when we look at the planet because it has bored through the outer cloud layer of methane. It rotates counter-clockwise every ten Earth days. The Great Dark Spot alows us to get a spy view of the lower layers of Neptune. The Great Dark Spot is dark, and very high in pressure, and it causes ice crystals of methane to form long and narrow cirrus clouds that span half the planet.
Neptune's atmosphere is similiar to the atmosphere of Uranus. It is composed mainly of hydrogen, with some helium, and little methane. The outer cloud layer of the planet, the stratosphere, is made up of mainly methane and causes the planet to appear blue. The next layer downward that we have seen is a layer of hydrogen sulfide. Storms are also generated hear. An examle is the white spot named "Scooter."
Being a gas giant, Neptune is mainly gas. It is composed mainly of hydrogen, helium, methane, and some other elements. It is thought that it has a core of non-conducting core of rock and ice. This explaines why its degree of magnetic axis is at an angle of 60š to its geographic axis and misses the center of the planet by more than 5,000 miles (8,000 km). The magnetic field is then caused by the movement of imurities in the watery outer layers of the planet. Neptune is mainly atmosphere. Neptune is the densest of all the gas giants. It has a density of 1.66 grams (.6 ounce) per cubic centimeter. It contains a greater portion of hevy elements than other gas giants.
Neptune has three rings. They are all around the equatorial region of the planet. The outer ring is composed of tiny dust particles which causes it to shine from certain anglesand is 39,000 miles (63,000 km) from the planet. Inside this ring is the second ring of the same composition but is very narrow. The second ring is 6,200 miles (10,000 km) closer to the planet than the outer ring and is only 12.5 miles (20 km) wide. The third ring and the closest to Neptune, another 6,200 miles (10,000 km) closer, is nicknamed "Fuzzy" because it is broad and difuse.
Neptune has two moons, Triton and Nereid, and six moonlets. Most of these were discovered by the Voyager probe that passed Neptune and observed it. The smaller moonlets of Neptune all orbit the planet in its equatorial plane. All are to small to have gravity and so are irregular shaped. They are also all dark, reflecting very little light. They have the characteristic of many meteorite collisions. The closest to the planet is N6. It was discovered in 1989 and orbits the planet at a distance of 30,000 miles (48,200 km). The farthest from the planet is N1 and it orbits the planet at a distance of 73,000 miles (117,600 km). N1 is also the largest moonlet of Neptune.
Nereid is the smaller of the two moons of Neptune. In fact, it is barely any larger than the moonlets. Nereid orbits Neptune once every 360 Earth days. It may have been "captured" by Neptune because its angle of orbit is at about 30š to Neptune's equatorial plane.
Triton is Neptune's largest moon. It has a diameter of 1, 690 miles (2,720 km), which is smaller than our moon. The difference between Triton and our moon is that Triton is highly reflective of light that reaches the it. An odd thing about Triton is that it orbits the planet in the opposite direction than the planet's rotation. Triton has a dark northern hemisphere with a pinkish southern polar cap. Triton is the coldest moon in our solar system because it reflects so much light. It is an astonishing -393šF (-236šC). Triton also has an atmosphere. The atmosphere of Triton is composed mainly of nitrogen. Triton is composed mainly of nitrogen, methane, and frozen water. Triton is still active although not as much as it used to be. There are still active volcanoes and geysers that erupt on Triton's surface. Triton orbits Neptune every 5.88 days at a distance of 220,000 miles (355,300 km). Eventually, because of Triton's unstable orbit, it will be pulled into Neptune.
Average distance from the sun . . . . . . . . . . 2,800,000,000 miles (4,500,000,000 km)
Average Temerature . . . . . . . . . . . . . . . . . -210šF (-350šC)
Diameter . . . . . . . . . . . . . . . . . . . . . . . . .30,200 miles (48,600 km)
Moons . . . . . . . . . . . . . . . . . . . . . . . . . .Total: 8:Triton, Nereid, and six moonlets: N1-N6
Orbit . . . . . . . . . . . . . . . . . . . . . . . . . . . 164.79 years
Day. . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 hours 3 minutes
Density . . . . . . . . . . . . . . . . . . . . . . . . . 1.64 times water's