This chart shows the differences between Proteus and Neptune. To change the planets/moons being compared, change one or more of the form fields at the bottom and click Refresh.

	Proteus	Neptune
Discovered By	S. Synnott, Voyager 2	Urbain Le Verrier, John Couch Adams, Johann Galle
Date of Discovery	1989	23 September 1846
Average Orbit Distance	117,646 km	4,498,396,441 km
Perihelion/Perigee (closest)	117,587 km	4,459,753,056 km
Aphelion/Apogee (farthest)	117,705 km	4,537,039,826 km
Equatorial Radius	210.0 km	24,622 km
Equatorial Circumference	1,319.5 km	154,704.6 km
Volume	38,792,386 km3	62,525,703,987,421 km3
Mass	50,355,259,352,065,700,000 kg	102,410,000,000,000,000,000,000,000 kg
Density	1.3 g/cm3	1.638 g/cm3
Surface Area	554,176.94 km2	7,618,272,763 km2
Equatorial Surface Gravity	0.76 m/s2	11.15 m/s2
Escape Velocity	644 km/h	84,816 km/h
Mean Orbit Velocity	27,450.7 km/h	19,566 km/h
Orbit Eccentricity	0.0005	0.00859048
Orbit Inclination to Ecliptic	0.075 degree	1.77 degrees
Orbit Circumference	739,191.57 km	28,263,736,967 km