Puck (moon)

Voyager 2 Stephen P. Synnott

Puck ( also Uranus XV) is the twelfth and one of the medium of the 27 known moons of the planet Uranus.

  • 3.1 size
  • 3.2 Internal structure
  • 3.3 Surface

Discovery and designation

Puck was discovered on December 30, 1985 by the astronomer Stephen P. Synnott on photographic images of the Voyager 2 spacecraft. He was the first moon, which was discovered by the flyby of the probe. The discovery was announced on 9 January 1986 by the International Astronomical Union ( IAU); the moon first received the provisional designation S/1985 U 1

Puck in William Shakespeare's comedy A Midsummer Night's Dream a tricky spirit who travels with the fairies at night around the world. Puck, also Gutfreund Robin (Robin Goodfellow ) called, is the familiar court jester of the elf king Oberon.

Puk, which was borrowed from the Baltic popular belief ( Pukis ), is found in many European legends, as in the Celtic ( Puca ) and Germanic mythology as well as in the Norse sagas and the English folklore.

All the moons of Uranus are named after characters from Shakespeare or Alexander Pope. The first four moons discovered Uranus ( Oberon, Titania, Ariel, Umbriel ) were proposed by John Herschel, the son of Uranus discoverer William Herschel, named. Later, the tradition of naming was retained.

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Orbit

Puck orbiting Uranus on a prograde, nearly perfectly circular orbit at an average distance of about 86,000 km (about 3,365 Uranus radii ) from the center, or about 60,400 km above the cloud tops. The orbital eccentricity of 0.00012, the orbit is inclined 0.319 degrees from the equator of Uranus.

The orbit of the next inner moon Perdita is an average distance of 9600 km pucks orbit, that of the next outer moon Mab 11.7 thousand kilometers.

Puck is in the midst of two Uranus rings; the outer edge of the inner current ν ( Ny ) dust ring is located in the middle around 16,100 km from Puck orbit, and the inner edge of the outer μ ( My) dust ring lies almost exactly on the orbit of Puck.

Puck Uranus rotates in 18 hours, 17 minutes. Because puck is moved close to the synchronous orbit and a good hour longer for a round rotates as needed Uranus, it follows that puck for a fictitious observer only good all Uranus 17.5 days on the horizon once or goes down, which means that he is about 8.75 days Uranus in the sky.

Rotation

It is believed that rotates synchronously and its puck axis having an inclination of 0 °.

Physical Properties

Size

Puck has a mean diameter of 162 km, making it the sixth-largest moon in the Uranus system. However, it is possible that this could be exceeded by the 1997 discovered irregular moon Sycorax, this should be darker than expected. Despite its small size puck seems remarkable round, the ratio of the axes is only 0.97 ± 0.04.

Internal construction

Its mean density is significantly lower than the density of the Earth at 1.3 g/cm3 and points out that the moon is composed mainly of water ice. Spectral analysis by the Hubble Space Telescope and ground-based telescopes to confirm absorptions of water ice. He seems to consist of a mixture of ice and dark material that appears to be similar to that found in the rings. This dark material may be arising out of a rock or by radioactive radiation from the sun organic material. The fact that Puck has no craters with bright edges, suggests that he has to have no differentiated structure. On its surface, the acceleration due to gravity is 0.029 m/s2, this represents only about 3 ‰ of the earthly.

Puck has a very low albedo of 0.11, i.e., 11 % of the incident solar light is reflected from the surface. It is thus a relatively dark sky body.

Surface

The average surface temperature of puck is on between -184 ° C and -209 ° C ( 89-64 K ) is estimated.

In the spectrum of light the surface of Puck appears gray. The surface shows cratered strong. The largest crater praise has a diameter of about 45 km. So far, three of the craters are named on Puck, according to the USGS nomenclature mischievous or malevolent spirits of the European mythologies.

Research

As Puck was discovered early enough to make him still installed in the observation program of the Voyager 2 spacecraft, he was photographed on 24 January 1986 in a minimum distance of 492,616 km and a low-resolution images of the surface are sent to Earth. He was the only one of the newly discovered when flying past the moon, which could be explored in somewhat more detail.

Since then, the Uranus system of ground-based observations as well as the Hubble Space Telescope has been studied intensively. The orbital parameters of Puck could be clarified.

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