Helike , also known as , is a

moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...

. It was discovered by a team of astronomers from the

University of Hawaii A university () is an educational institution, institution of tertiary education and research which awards academic degrees in several Discipline (academia), academic disciplines. ''University'' is derived from the Latin phrase , which roughly ...

led by Scott S. Sheppard in 2003, and given the temporary designation . Helike is about 4 kilometres in diameter, and orbits Jupiter at an average distance of 20.54 million kilometres in 601.402 days, at an

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

of 155° to the

ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. Fr ...

(156° to Jupiter's equator), in a retrograde direction and with an

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-Centre (geometry), center, in geometry * Eccentricity (g ...

of 0.1375. Its average orbital speed is 2.48 km/s. It was named in March 2005 after

Helike Helike (; , pronounced , modern ) was an ancient Greek polis or city-state that was submerged by a tsunami in the winter of 373 BC. It was located in the Regional units of Greece, regional unit of Achaea, northern Peloponnesos, two kilometres ( ...

, one of the nymphs that nurtured

Zeus Zeus (, ) is the chief deity of the List of Greek deities, Greek pantheon. He is a sky father, sky and thunder god in ancient Greek religion and Greek mythology, mythology, who rules as king of the gods on Mount Olympus. Zeus is the child ...

(Jupiter) in his infancy on

Crete Crete ( ; , Modern Greek, Modern: , Ancient Greek, Ancient: ) is the largest and most populous of the Greek islands, the List of islands by area, 88th largest island in the world and the List of islands in the Mediterranean#By area, fifth la ...

. Helike belongs to the Ananke group.

References

Ananke group Moons of Jupiter Irregular satellites Discoveries by Scott S. Sheppard Astronomical objects discovered in 2003 Moons with a retrograde orbit {{Jupiter-stub