Erriapus , or Saturn XXVIII (28), is a
prograde irregular satellite
In astronomy, an irregular moon, irregular satellite, or irregular natural satellite is a natural satellite following an orbit that is irregular in some of the following ways: Distant; inclined; highly elliptical; retrograde. They have often be ...
of
Saturn
Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 tim ...
. It was discovered by
Brett Gladman,
John J. Kavelaars and colleagues in 2000, and given the temporary designation S/2000 S 10. It was named Erriapo in August 2003 after ''Erriapus'' (also rendered ''Erriappus''), a giant in
Gaulish mythology; the name was changed from
dative
In grammar, the dative case (abbreviated , or sometimes when it is a core argument) is a grammatical case used in some languages to indicate the recipient or beneficiary of an action, as in "", Latin for "Maria gave Jacob a drink". In this exampl ...
''Erriapo'' to
nominative
In grammar, the nominative case ( abbreviated ), subjective case, straight case, or upright case is one of the grammatical cases of a noun or other part of speech, which generally marks the subject of a verb, or (in Latin and formal variants of E ...
''Erriapus'' per
IAU
The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...
conventions in late 2007.
Erriapus is about 10 kilometres in diameter, and orbits Saturn at an average distance of 17.5 Gm in 871 days.
As a member of the
Gallic group of irregular satellites, which share similar orbital characteristics and a light-red colour, Erriapus is hypothesized to have its origin in the break-up of a common progenitor of the group,
or to be a fragment of its largest member,
Albiorix.
It has a rotation period of , and is thought to rotate on its side, giving it similar seasons to those of
Uranus
Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a Supercritical fluid, supercritical phase of matter, which astronomy calls "ice" or Volatile ( ...
.
With a fairly elongated shape, it is a candidate for a
contact binary
In astronomy, a contact binary is a binary star system whose component stars are so close that they touch each other or have merged to share their gaseous envelopes. A binary system whose stars share an envelope may also be called an overcontac ...
or binary moon.
References
External links
David Jewitt pages
{{DEFAULTSORT:Erriapus (Moon)
Gallic group
Moons of Saturn
Irregular satellites
Astronomical objects discovered in 2000
Moons with a prograde orbit