Proteus (moon)
Voyager 2 Stephen P. Synnott Bradford A. Smith
Proteus ( Neptune VIII) is the second largest moon of the planet Neptune. He is regarded as the largest non - spherical natural satellite of a planet.
Discovery and designation
Proteus was happening around June 16, 1989 by Stephen P. Synnott and Bradford A. Smith on pictures of the Voyager 2 spacecraft, the Proteus in August 1989, discovered. The discovery was announced on 7 July 1989 by the International Astronomical Union ( IAU); the moon got the provisional designation S/1989 N 1
Although Proteus is the second largest of Neptune moon, and that is greater than the Nereid he was not discovered from Earth because it moves so close to Neptune that he is outshone by its reflected sunlight, and therefore is not surprising that he only 40 years could be detected by Nereid and 143 years after Triton.
On September 16, the moon of the IAU by Proteus was named (the " Old Man of the Sea" ), a sea god of Greek mythology. Although he really is an older deity Proteus sometimes referred to as the son of Poseidon (Roman Neptune) is described. He was careful, on the island of Pharos, the seals and other marine creatures of Poseidon and had the gift of prophecy, but was reluctant to reveal his knowledge, which is why it was hard to elicit from him a prophecy. He tried to escape the question by assuming different shapes.
Web properties
Orbit
Proteus orbits Neptune on a prograde, nearly perfectly circular orbit at an average distance of 117,647 kilometers (about 4,751 Neptune radii ) from its center, ie 92.9 thousand kilometers above the cloud tops. The orbital eccentricity of 0.00053, the orbit is inclined 0.524 degrees from the equator of Neptune.
The orbit of the next inner moon S/2004 N 1 is 12,364 km of Proteus ' Orbit removed in about five times the distance, namely 237.1 thousand kilometers. The next outer moon Triton
Proteus orbits Neptune in 1 day, 2 hours, 56 minutes and 8.0 seconds.
Rotation
The rotation period is equal to the round trip time and has thus Proteus, such as the Earth's moon, a synchronous rotation to.
Physical Properties
Proteus is an irregularly shaped body with dimensions of 436 × 416 × 404 km. Many scientists believe that Proteus has the maximum length of a non-circular body in proportion to its density. He's just so great that not even forcing him his own gravity into a spherical shape. The somewhat smaller Saturn 's moon Mimas has a more rounded shape, although this has slightly less mass than Proteus, which perhaps may be due to the slightly smaller density of Mimas. Slightly larger than Saturn 's moon Enceladus has more mass and a higher density and is, like the Uranus moon Miranda also comparable large, spherical as Proteus.
Proteus has a dark surface with an albedo of 0.096, which means that only about ten percent of the incident sunlight is reflected. He is one of the darkest large to mid-sized moons in the solar system. The total area is 2,195,000 km2, which is slightly greater than that of Saudi Arabia. The average surface temperature is set at -222 ° C ( ~ 51 K ) is estimated.
Its surface is heavily cratered and has next to some of the larger craters exhibit also linear, grave -like structures. The largest crater, spanning about half the diameter of the moon, was named Pharos. Apparently, the moon was formed by no geological processes after its creation.
Research
Although in the Voyager 2 flyby based on the priority of a nearby Triton Passage no Naherkundung was possible, Proteus could happen in 97.86 thousand km distance and images are captured at a resolution of up to 1.35 km / pixel. Proteus was large enough and was soon enough discovered that it could still be built into the monitoring program as one of the six newly discovered by the probe Neptune's moons. In order to avoid blurring of the images by the movement of the probe, they were made in six gray levels due to the reduction of the amount of data.
Since the flyby of the Neptune system ground-based observations as well as the Hubble Space Telescope has been studied intensively. 2002 - 2003 the Keck Observatory observed the system by means of adaptive optics, which Proteus was again observed.