Neptune
 |
- Neptune is the 8th planet from the Sun.
- The planet Neptune has a diameter of 31,000 miles.
- At a distance of 2.793 billion miles,
it takes 165 years to circle the Sun.
- One day lasts 15 hours, 48 minutes of Earth time.
On its approach to
Neptune in August 1989, Voyager 2
captured this image of the fourth and outermost of the giant gas
planets. PHOTO / NASA |
Facts about Neptune
A. Neptune is named after the Roman god of the sea. The two largest moons of Neptune are Triton and Nereid. Triton
is the Roman name for mermen, and Nereid the name for mermaids, thus keeping with the oceanic theme. Neptune was
discovered simultaneously by English and French astronomers.
B. Neptune is approximately of the same size and composition as Uranus, but has a radically different atmosphere.
Because it spins vertically on its axis, rather than on its side, it has a more dynamic surface, with the fastest
winds in the solar system at well over a thousand miles per hour.
C. Neptune was once seen to have a large blue spot, discovered by the Viking Space Probe, much like the Great
Red Spot on Jupiter. However, recent pictures from the Hubble Space Telescope show that this spot has disappeared.
D. Neptune's moon, Triton, joins Saturn's moon, Titan, as the only other moon in the solar system with its own
atmosphere. It is the largest of Neptune's many moons.
Earn The Astronomical League's Award for Observing the Solar System
 Planetary
Club Rules and Regulations
Comparative Data on the Jovian Planets and Pluto
| Quantity |
Jupiter
|
Saturn
|
Uranus
|
Neptune
|
Pluto
|
| Equatorial diameter (Km) |
142796
|
120000
|
50800
|
48600
|
3300-2800(?)
|
| Density (kg/cm(3)) |
1330
|
706
|
1270
|
1700
|
2000?
|
| Mass (Earth=1) |
1318.7
|
743.6
|
14.6
|
17.2
|
0.0025?
|
| Surface gravity (Earth=1) |
2.643
|
1.159
|
1.11
|
1.21
|
?
|
| Escape velocity (km/s) |
60.22
|
32.26
|
22.5
|
23.9
|
?
|
| Mean distance from sun (AU) |
5.2028039
|
9.5388437
|
19.181843
|
30.057984
|
39.4
|
| Mean distance from sun (miles) |
4.836x10(8)
|
8.8722x10(8)
|
1.7837x10(8)
|
2.7946x10(8)
|
3.6642x10(8)
|
| Mean distance from sun (10(6)Km) |
778.3
|
1427
|
2869
|
4497.1
|
5900
|
| Orbital period (Earth years) |
11.867
|
29,461
|
84,013
|
164,793
|
247.7
|
| Orbital period (Earth days) |
4334.3
|
10,760
|
30,685
|
60,189
|
90,465
|
| Orbital velocity (Km/sec) |
13.06
|
9.64
|
6.81
|
5.43
|
4.74
|
| Ave. Surface Temperature (K) |
125
|
95
|
60
|
60
|
|
|
