Kallichore.space

Irregular moon of Jupiter (retrograde) · Outer Jovian system · Carme group

Kallichore

Jupiter XLIV · S/2003 J 11

An elongated, four-kilometre moon that ESA’s Juice spacecraft might fly past in October 2031.

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Kallichore at a glance
Object typeIrregular, retrograde moon of Jupiter[1]
GroupCarme group[1]
Discovered6 Feb. 2003 by Scott S. Sheppard (Canada–France–Hawaii Telescope)[1]
Named30 March 2005, after Callichore[1]
Diameter≈ 3.5–6.1 km (2025 stellar occultation)[1]
Albedo≈ 3.7%[1]
ShapeElongated, axis ratio a/b ≥ 1.53 (Hubble)[1]
BrightnessApparent magnitude ≈ 23[1]
Mean distance≈ 23.0 million km from Jupiter[2]
Orbital period≈ 714 days[2]
Inclination≈ 165° (retrograde)[2]
Possible flybyJuice, < 1 million km on 7 Oct. 2031[1]

A future flyby target

Kallichore is a potential flyby target for ESA’s Juice mission, predicted to pass within 1 million km of the moon on 7 October 2031.[1] Juice launched on 14 April 2023 and is expected to reach Jupiter in July 2031.[3]

Measured by a star

Observations of a stellar occultation in 2025 show Kallichore is between 3.5 and 6.1 km across, with a dark surface of albedo around 3.7%.[1] An occultation happens when one object hides another passing behind it.[4]

Elongated rubble?

Hubble saw Kallichore’s brightness change by at least 0.46 magnitudes within 1.25 hours, suggesting an elongated shape with an axis ratio of at least 1.53. It is suspected to be a rubble pile, like asteroids Ryugu and Bennu.[1]

Carme family

Kallichore shares Carme’s orbit type. The Carme group’s parent likely came from the outer Solar System, as a D-type asteroid or a centaur or trans-Neptunian object.[1]

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Orbit

Kallichore orbits backwards at an average of about 23.0 million km, ranging roughly 17.2–28.8 million km over 714 days.[2] Over 1,000-year simulations its semi-major axis varies from 22.0 to 24.4 million km, with nodal and apsidal precession periods of 86.3 and 49.1 years.[1]

Jupiter Callisto (1.88 million km)Himalia (11.44 million km) farthest ≈ 28.8 million km closest ≈ 17.2 million km
Top-down orbit of Kallichore to scale, computed from JPL orbital elements (a ≈ 23.02 million km, e ≈ 0.253).[2] Callisto and Himalia orbits shown for comparison.[2] Mean orbital elements; the real orbit is tilted steeply and shifts over time, so this top-down view flattens it onto one plane.

The name

It was named on 30 March 2005 after Callichore, one of the Muses and a daughter of Zeus. Its “e” ending marks its retrograde orbit.[1]

Read more

Will Juice fly past Kallichore?

The 2031 opportunity, and why the moon’s position must be pinned down first.

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Measuring a tiny moon with a star

How a 2025 stellar occultation sized Kallichore.

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Is Kallichore a rubble pile?

What Hubble’s brightness changes reveal about its shape.

Read →

Sources

  1. Kallichore (moon) — Wikipedia
  2. Planetary Satellite Mean Elements — NASA JPL Solar System Dynamics
  3. Jupiter Icy Moons Explorer — Wikipedia
  4. Occultation — Wikipedia
  5. Rubble pile — Wikipedia

Figures are rounded; where sources differ we note it. Spotted an error? Tell us.