|
Neptune
The last of the giant planets, Neptune was first observed by multiple
observers including Adams, Galle, and Le Verrier in 1946. Like Uranus,
Neptune is made of fairly evenly distributed materials with no stratification.
Unlike the other planets, Neptune is made up of more ice and rock than
hydrogen, (15% against Uranus 83%). It has a small rocky core
with a methane rich atmosphere which absorbs red light, giving Neptune
its appropriate deep sea blue color. Neptune also has the fastest winds
in the Solar System, clocked at some 2000 miles per hour (3200km/h).
Despite its distance from the Sun, Neptune is incredibly hot, radiating
back twice the heat it receives from the Sun.
Like Jupiter, Neptune has its own Great Spot. However, Neptunes
spot is only as big as Earth, half the size of the spot found on Jupiter,
and far from stable. It can disappear from one hemisphere and reappear
on the other. More permanent is the small spot on Neptunes Southern
Hemisphere and the small white cloud plume above it. This cloud zips
around the planet in a regular way prompting scientists to give it the
nickname the scooter.
Neptune has 8 moons, the largest of which is Triton. It also has a
very thin ring system that was thought to be incomplete for a long time.
Neptune shares the position of last planet in the Solar System with
Pluto, whose orbit occasionally runs inside Neptunes.
|
Diameter
|
49, 482 km
|
|
Mass
|
1.02 × 1026kg
|
|
Mean Distance from
sun
|
4,504,300,000 km
|
|
Mean Density
|
1.64 g/cm3
|
|
Rotational Period
|
0.66 Earth days
|
|
Orbital Period
|
164.8 Earth years
|
|
Mean Orbital Velocity
|
5.45 km/s
|
|
Atmosphere
|
79% hydrogen, 18%
helium, 3% methane
|
|
Average Surface Temperature
|
-173°C
|
|
Equatorial Surface
Gravity
|
11 m/s2
|
|