Philophrosyne (moon)
A small retrograde irregular moon of Jupiter, recovered after being lost.
Philophrosyne (Jupiter LVIII, formerly S/2003 J 15) is a moon of Jupiter. It was first spotted in 2003 by a University of Hawaiʻi team led by Scott S. Sheppard, but astronomers lost track of it afterward. The moon was found again in 2017, and that year it got its official number.
This moon is roughly 2 kilometers wide. It travels around Jupiter at an average distance of 22,721,000 km, taking 699.676 days to complete one orbit. Its path is tilted 142° to the ecliptic (also 142° to Jupiter’s equator), moves in the opposite direction of Jupiter’s rotation, and has an orbital eccentricity of 0.0932. Philophrosyne belongs to the Pasiphae group—a set of retrograde, irregular moons whose orbits lie between about 22.8 and 24.1 Gm from Jupiter, with inclinations near 150–155°.
The moon got its name in 2019. It comes from Philophrosyne, the ancient Greek spirit of welcome, friendliness, and kindness, daughter of Hephaestus and Aglaea and granddaughter of Zeus. The name was chosen through a contest on Twitter, suggested by users including CHW3M Myth Experts (a grade‑11 history class studying Greek and Roman philosophy in 2019), Victoria (@CharmedScribe), and Lunartic (@iamalunartic), who also helped name another Jovian moon, Eupheme.
Quick Facts
- Pronounced
- f · ɪ · l · ə · ˈ · f · r · ɒ · s · ə · n · iː or - · ˈ · f · r · ɒ · z · ə · n · iː
- Adjective
- Philophrosynean f · ɪ · ˌ · l · ɒ · f · r · ə · z · ə · ˈ · n · iː · ə · n
- Named After
- Φιλοφροσύνη Philophrosynē
- Discoverer
- Scott Sheppard et al.
- Discovered
- 2003
- Mpc Name
- Jupiter LVIII
- Observation Arc
- 2003 · 2024 / 2024-12-03 (last obs)
- Inclination
- 143.6°
- Eccentricity
- 0.194
- Period
- −701.3 days
- Satellite Of
- Jupiter
- Group
- Pasiphae group
Facts from the source article.
Lore & Background
Philophrosyne was discovered in 2003 by a team of astronomers from the University of Hawaiʻi led by Scott S. Sheppard et al., but then lost. It was recovered in 2017 and given its permanent designation that year. The moon is about 2 kilometres in diameter and orbits Jupiter at an average distance of 22,721,000 km in 699.676 days, with an inclination of 142° to the ecliptic (142° to Jupiter's equator), in a retrograde direction and with an eccentricity of 0.0932. It belongs to the Pasiphae group, a set of retrograde irregular moons that orbit Jupiter between 22.8 and 24.1 Gm, at inclinations of roughly 150–155°.
Reader's Guide
Philophrosyne's significance lies in its recovery after being lost for over a decade, highlighting the challenges of tracking small irregular moons. Its permanent designation in 2017 and naming in 2019 reflect ongoing efforts to catalog Jupiter's many satellites. The moon's name, chosen via a Twitter contest, connects it to ancient Greek mythology as the spirit of welcome, friendliness, and kindness, daughter of Hephaestus and Aglaea and granddaughter of Zeus. The naming contest involved users including CHW3M Myth Experts, an 11th-grade history class studying Greek and Roman philosophy as of 2019, Victoria, and Lunartic, who also helped name another Jovian moon, Eupheme. As a member of the Pasiphae group, Philophrosyne contributes to understanding the dynamics of retrograde irregular moons, which are thought to be captured asteroids or fragments from collisions.
Did You Know?
- Philophrosyne was discovered in 2003 but then lost, and was recovered in 2017.
- It is about 2 kilometres in diameter and orbits Jupiter in a retrograde direction.
- The moon belongs to the Pasiphae group, which orbits Jupiter between 22.8 and 24.1 Gm.
- Its name was chosen from a Twitter contest, suggested by users including an 11th-grade history class.
More in Moons of Jupiter 1-24
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