Thursday, 10 November 2011

hi!! we are Sandra and Irene, enjoy it!!!





NEPTUNE

-WHERE NEPTUNE’S NAME CAME FROM?

This planet was first located through mathematical predictions rather than through regular observations of the sky. When Uranus didn’t travel as astronomers expected it to, Le Verrier a French mathematician proposed the position of an unknown planet that could cause changes in Uranus’ orbit. Le Verrier sent his prediction to Johann Galle, who found during his first night on 23 September 1846, he decided to call the planet with the name of the roman god of the sea: Neptune

MASS

1.0241 x 1026 kg

DENSITY

Metric: 1.638 g/cm3

By Comparison: 0.297 x Earth

VOLUME

Scientific Notation: 6.25257 x 1013 km3

By Comparison: 57.723 x Earth

SURFACE

Scientific Notation: 7.6183 x 109 km2

By Comparison: 14.980 x Earth

TEMPERATURE

Metric: -214 °C

Scientific Notation: 59 K

ATMOSPHERIC CONSTITUENTS

Hydrogen, Helium, Methane

Scientific Notation: H2, He, CH4

Tilt of axis (degrees)

29.56

LENGHT OF DAY 0.671 Earth days 16.11000 hours

LENGTH OF YEAR 164.79132 Earth years 60190.03 Earth days



DIAMETER

Neptune has an equatorial diameter of 49,500 kilometres (30,760 miles).

Average distance from Sun

The mean distance of Neptune from the Sun (in km) is about 4,504,300,000.

ATMOSPHERE: COMPOSITION AND ACTIVITIES

Neptune's atmosphere mainly consists of molecular hydrogen (H2) 80%, helium (He) 19% and methane (CH4) 1.5%. It also contains small amounts of hydrogen deuteride (HD) and ethane (C2H6). The average temperature of Neptune at cloud top is -220oC. It has an extremely hot core at about 5150oC, hotter than the surface of the sun.

It is most likely that Neptune has a small solid core of a rocky material about the mass of the Earth surrounded by a layer of liquid which is probably Water with molecules of methane and ammonia. The temperature of this water is many times the 100oC that water boils at on Earth, but the extremely high pressure or the Neptunium atmosphere keeps the particles from escaping the water.

When Voyager visited Neptune it measured wind speeds of up to 2400 km/h, the highest recorded on any planet due to its heat producing core causing rising heat. Also because of this core Neptune Radiates more than twice as much energy as it receives from the sun.

Although Neptune is considered one of the great Jovian planets (or gas giants), it is not really a true Jovian as unlike Jupiter (the planet which gives its name to Jovian) Neptune is mostly Rock and water rather than gas.

Astronomers think that Neptune formed from frozen water and rock supplied by commet-like material from the outer regions of the solar system.

NEPTUNE’S COMPOSITION

Neptune (like Uranus) is composed of various ices and rock with about 15% hydrogen and a little helium. It may not have a distinct internal layering but rather to be more or less uniform in composition. There is most likely a small core of rocky material. Its atmosphere is mostly hydrogen and helium with a small amount of methane.


SATELLITES

all the moons of Neptune are named for characters from greek and roman mythology associated with Neptune or Poseidon. Irregular satellites are named for the Nereid’s daughters and the attendants of Neptune.


TRITON: Lassell was an England’s

astronomer who

discovered the largest

of Neptune’s satellites on 10 October

1846, 15 days after a Berlin observatory

discovered Neptune. Firstly he thought

that he had found rings, but this was a

distortion caused by his telescope. But

later he discovered he was wrong.

Triton’s icy surface reflects the little amount of sunlight that reaches the moon, this is one of the coldest object in the solar system 400 degrees F.

Triton is also the only moon in the solar system that circles its planet in the opposite to the planets rotation. This means that is an independent object captured by Neptune’s gravity. This gravity makes the moon to get closer and closer to the planet. Millions years from now triton will become close enough for gravitational forces to break it apart possibly forming a ring

around Neptune.

NEREID (sea-nymphs

in greek) :

was discovered on 1 May 1949 by Gerard P. Kuiper with a ground base telescope. It was the last satellite of Neptune to be discovered before voyage 2’s discoveries. Nereid is unique because it has one of the most eccentric orbits of any moon of our system. The moon requires 360 earth days to make an orbit, this orbit suggest that Nereid may be captured asteroid or kuiper belt object or that it was greatly disturbed during the capture of Neptune’s largesto moon (triton).

NAIAD:



There are more satellites but this are smaller and we don’thave many information about them this satellites are :

THALASSA, DESPINA, GALATEA, LARISSA, PROTEUS, HALIMEDE, PÁSMATE, SAO, LAOMEDEIA, NESO

RINGS

When voyager 2 cameras demonstrated that there were incomplete arcs around Neptune, the ring system contain several faint rings, the most important are Liberty, Equality and Fraternity. The gravitational effects of Galatea, a moon just inward from the ring are believed to confine the arcs.

Some of the arcs detected by Voyager 2 are Adamas ring 63,000km from the centre of Neptune, le varrier Ring is at 53,000km, Galle ring is at 42,000km and Arago ring at 57,000km

Exploration missions

The exploration of Neptune has only begun with one explorer, Voyager 2, which visited on August 25, 1989. The possibility of a Neptune Orbiter was discussed, yet other than that, no other missions have been given serious thought.


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