Hyperion (moon)

W. C. Bond, G. P. Bond, W. Lassell

Hyperion ( Saturn VII ) is a mid-sized moons of Saturn.

Discovery

Hyperion was discovered on 16 September 1848 by William Cranch Bond, George Phillips Bond and William Lassell.

The moon was named after the Titans Hyperion in Greek mythology. Hyperion was published shortly after a 1847 publication of the astronomer John Herschel ( Results of Astronomical Observations made ​​at the Cape of Good Hope), in which he proposed the name of the then known seven moons of Saturn, discovered. Lassell, who sighted Hyperion two days after the Bonds, Herschel's naming scheme was known. In line with this, he suggested the name Hyperion.

Path data

Hyperion orbits Saturn at an average distance of 1.4641 million kilometers in 21 days, 6 hours and 43 minutes. The track has an eccentricity of 0.0175 and 0.568 ° inclined relative to the equatorial plane of the Saturn.

Structure and physical data

Hyperion is one of the most irregularly shaped body in the Solar System for its size. It has an area of ​​360 × 280 × 225 km.

Apparently Hyperion is a fragment of a larger source body, which is broken at one impact event. On its surface a huge, 10 km deep crater with a diameter of 120 km is visible.

With 0.544 g/cm3 has Hyperion, like most of Saturn's moons, a very low density. He's obviously made ​​up predominantly of porous water ice with small amounts of silicate rock.

In contrast to most of Saturn 's moons Hyperion has with an albedo of 0.25 on a dark surface that could result from the deposition of a dark material. According to studies of the Cassini spacecraft in 2005 are in the dark deposits around hydrocarbon compounds.

Rotation

Recordings of the Voyager 2 spacecraft and ground-based photometric studies showed that Hyperion's rotation is chaotic, its rotational axis fluctuates in completely unpredictable ways. He is the only known moon in the solar system that exhibits this behavior, although computer simulations have shown that may have rotated in such a way in the past, other irregularly shaped moons.

Hyperion is unique among moons a special place. It is highly irregular in shape, its orbit is eccentric and it is located at a relatively short distance from a large moon, Titan, with whom he runs around the planet in a 3:4 resonance. These factors limit the ways in which a stable rotation is possible.

Observation and approximations

Hyperion is a light faint object with an apparent magnitude of 14.2 m. To watch him, a larger telescope is required.

On 26 September 2005 the same probe examined the moon in another flyby closer, in which they could approach very close to only 500 km away. The previously best shots of the moon, which show an unusual surface and support the assumption of a relatively porous consistency emerged.

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