''There is also an asteroid called 9313 Protea.

{| class="toccolours" style="margin-left: 1em; float: right" style="margin: inherit; font-size: larger;"|Proteus Discovery Discovered by Voyager 2
Stephen P. Synnott Discovered on June 16, 1989 Orbital characteristics (Epoch J2000) Semi-major axis 117,647 km (0.00079 AU) Eccentricity 0.0005 Periapsis 117,588 km Apoapsis 117,706 km Orbital period 1.122315 d Orbital circumference 739,200 km (0.005 AU) Orbital velocity max: 7.629 km/s
mean: 7.625 km/s
min: 7.621 km/s Inclination 28.92° (to Ecliptic)
0.526° (to Neptune's equator)
0.026° (to the local Laplace plane)
Satellite of Neptune Physical characteristics Diameter 436 × 416 × 402 km Surface area ~2,195,000 km² Volume ~38,177,000 km³ Mass 5.0 kg Mean density 1.3 g/cm³ Surface gravity ~0.075 m/s² (0.001 g) Escape velocity ~0.18 km/s Rotation period synchronous Axial tilt zero Albedo 0.10 Surface temp.

min	mean	max
K	~51 K	K

Atmospheric pressure 0 kPa Proteus (proe'-tee-əs, IPA , Greek Πρωτέας), or Neptune VIII, is the second largest Neptunian moon. It is named after Proteus, the shape-changing sea god of Greek mythology.

Discovery

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Proteus was discovered from the images taken by Voyager 2 probe during the Neptune flyby in 1989. It received the temporary designation S/1989 N 1. Stephen P. Synnott and Bradford A. Smith announced (IAUC 4806) its discovery on July 7, 1989, speaking only of “17 frames taken over 21 days”, which gives a discovery date of sometime before June 16.

Physical characteristics

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Proteus is more than 400 kilometres in diameter, larger than Nereid, another moon of Neptune. However, it was not discovered by Earth-based telescopes because it is so close to the planet that it is lost in the glare of reflected sunlight. Proteus is one of the darkest objects in the solar system, as dark as soot; like Saturn's moon Phoebe, it reflects only 6 percent of the sunlight that strikes it. Proteus is very cratered showing no sign of any geological modification. It is also irregularly shaped; scientists believe Proteus is about as large as a body of its density can be without being pulled into a spherical shape by its own gravity. Saturn's moon Mimas has much more regular shape despite being less massive than Proteus.

See also

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• List of craters on Proteus

External links

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• IAU Circular 4806 describing the discovery of S/1989 N 1
• The Nine Planets – Proteus
• Views of the Solar System – Proteus, A Moon Of Neptune

Neptune's moons

Протей (спътник) | Proteu (satèl·lit) | Proteus (måne) | Proteus (Mond) | Proteo (luna) | Protée (lune) | Proteus (mjesec) | Proteo (astronomia) | Proteus (maan) | プロテウス (衛星) | Neptunmånen Proteus | Proteusz (księżyc) | Proteu (satélite) | Proteus (mesiac) | Proteus (kuu) | 海卫八