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Physical Characteristics Of Neptune

Since the Neptune Orbit so far from the sun, it receives very small amount of heat and indeed the uppermost region of the atmosphere is -218 °C (55 K). There is no solid surface due to the fact that Neptune is a gas giant. Atmospheric temperatures gradually rise as you go deeper inside Neptune due to an internal source of heat. It is thought that this may be leftover heat generated by in falling matter during the planet's birth, right now slowly radiating away into space. Neptune's atmosphere has the highest wind speeds in the solar system, up to 2000 km/h, thought to be powered by this flow of internal heat. The internal structure resembles that of Uranus.

Neptune consists of (molten) rock and metal, bounded by a blend of rock, water, ammonia, and methane. The atmosphere, extending perhaps 10 to 20 percent of the way towards the centre, is typically hydrogen and helium at high altitudes, but has increasing concentrations of methane, ammonia, and water as it approaches and finally blends into the liquid interior. The pressure at the centre of Neptune is millions of times more than that on the surface of Earth. Comparing its rotational speed to its degree of oblateness represents that it has its mass less concentrated towards the centre than does Uranus.

Neptune also resembles Uranus in its magnetosphere, with a magnetic field strongly tilted relative to its rotational axis at 47° and offset at least 0.55 radii (about 13,500 kilometres) from the planet's physical centre. Comparing the magnetic fields of the two planets, scientists think the extreme orientation may be characteristic of flows in the interior of the planet and not the result of Uranus' sideways orientation.

One disparity between Neptune and Uranus is the level of meteorological activity. Uranus is visually quite bland, while Neptune's high winds come with distinguished weather phenomena. The Great Dark Spot, an Earth-sized dark marking similar to the Great Red Spot of Jupiter, disappeared in 1994 but another reappeared afterward. Distinctive among the gas giants is the presence of high clouds casting shadows on the opaque cloud deck below.