Eirene is about 4 kilometres in diameter, and orbits Jupiter at an average distance of 23,974,000 km in 743.88 days, at an inclination of 166° to the ecliptic (167° to Jupiter's equator), in a retrograde direction and with an eccentricity of 0.307.
It belongs to the Carme group, made up of irregular retrograde moons orbiting Jupiter at a distance ranging between 23 and 24 Gm and at an inclination of about 165°.
Name
The moon was named in 2019 after Eirene (Εἰρήνη), the daughter of Zeus and Themis and the goddess of peace in Greek mythology; the name originated from a naming contest held on Twitter with sixteen tweets suggesting the name, most significantly by users Quadrupoltensor (@Quadrupoltensor) who first suggested the name and PaulR (@PJRYYC).[10][11][12]
^Sheppard, Scott S. (2017). "New Moons of Jupiter Announced in 2017". home.dtm.ciw.edu. Retrieved 27 June 2017. We likely have all of the lost moons in our new observations from 2017, but to link them back to the remaining lost 2003 objects requires more observations a year later to confirm the linkages, which will not happen until early 2018. ... There are likely a few more new moons as well in our 2017 observations, but we need to reobserve them in 2018 to determine which of the discoveries are new and which are lost 2003 moons.