Eupheme , also Jupiter LX, originally known as , is an outer

natural satellite A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are colloquially referred to as moons, a deriv ...

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 ...

, 2 km in diameter.

Discovery

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. The moon was lost following its discovery in 2003. It was recovered in 2017 and given its permanent designation that year.

Name

It was named in 2019 after Eupheme, the ancient Greek spirit of words of good omen, praise, acclaims, shouts of triumph, and applause, the daughter of

Hephaestus Hephaestus ( , ; wikt:Hephaestus#Alternative forms, eight spellings; ) is the Greek god of artisans, blacksmiths, carpenters, craftsmen, fire, metallurgy, metalworking, sculpture and volcanoes.Walter Burkert, ''Greek Religion'' 1985: III.2. ...

and Aglaea and granddaughter of

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 ...

. The name was suggested by

Twitter Twitter, officially known as X since 2023, is an American microblogging and social networking service. It is one of the world's largest social media platforms and one of the most-visited websites. Users can share short text messages, image ...

user Lunartic (@iamalunartic) in a naming contest held by the Carnegie Institute on the social network who concurrently helped in naming another Jovian moon Philophrosyne.

Orbit

Eupheme orbits Jupiter at an average distance of 19,622 Mm in 628.06 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 146° 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 ...

(146° 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 0.2507. It belongs to the Ananke group, retrograde irregular moons that orbit Jupiter between 19.3 and 22.7 Gm, at inclinations of roughly 150°.

References

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