| Neptune Statistics | |
|---|---|
| Discovered by | Johann Gotfried Galle |
| Date of discovery | September 23, 1846 |
| Mass (kg) | 1.024e+26 |
| Mass (Earth = 1) | 1.7135e+01 |
| Equatorial radius (km) | 24,746 |
| Equatorial radius (Earth = 1) | 3.8799e+00 |
| Mean density (gm/cm^3) | 1.64 |
| Mean distance from the Sun (km) | 4,504,300,000 |
| Mean distance from the Sun (Earth = 1) | 30.0611 |
| Rotational period (hours) | 16.11 |
| Orbital period (years) | 164.79 |
| Mean orbital velocity (km/sec) | 5.45 |
| Orbital eccentricity | 0.0097 |
| Tilt of axis (degrees) | 28.31 |
| Orbital inclination (degrees) | 1.774 |
| Equatorial surface gravity (m/sec^2) | 11.0 |
| Equatorial escape velocity (km/sec) | 23.50 |
| Visual geometric albedo | 0.41 |
| Magnitude (Vo) | 7.84 |
| Mean cloud temperature | -193 to -153°C |
| Atmospheric pressure (bars) | 1-3 |
| Atmospheric composition 85% 13% 2% | |
The following table is a summary of the rings of Neptune.
| Name | Distance* | Width | Thickness | Mass | Albedo |
|---|---|---|---|---|---|
| 1989N3R | 41,900 km | 15 km | ? | ? | low |
| 1989N2R | 53,200 km | 15 km | ? | ? | low |
| 1989N4R | 53,200 km | 5,800 km | ? | ? | low |
| 1989N1R | 62,930 km | < 50 km | ? | ? | low |
*The distance is measured from the planet center to the startof the ring.
| Moon | # | Radius (km) | Mass (kg) | Distance (km) | Discoverer | Date |
|---|---|---|---|---|---|---|
| Naiad | III | 29 | ? | 48,000 | Voyager 2 | 1989 |
| Thalassa | IV | 40 | ? | 50,000 | Voyager 2 | 1989 |
| Despina | V | 74 | ? | 52,500 | Voyager 2 | 1989 |
| Galatea | VI | 79 | ? | 62,000 | Voyager 2 | 1989 |
| Larissa | VII | 104x89 | ? | 73,600 | Voyager 2 | 1989 |
| Proteus | VIII | 200 | ? | 117,600 | Voyager 2 | 1989 |
| Triton | I | 1,350 | 2.14e+22 | 354,800 | W. Lassell | 1846 |
| Nereid | II | 170 | ? | 5,513,400 | G. Kuiper | 1949 |