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”’S/2018 J 4”’ is a small outer [[natural satellite |
”’S/2018 J 4”’ is a small outer [[natural satellite of Jupiter]] discovered by [[Scott S. Sheppard]] on 11 May 2018, using the 4.0-meter [[VÃctor M. Blanco Telescope]] at [[Cerro Tololo Observatory]], [[Chile]]. It was announced by the [[Minor Planet Center]] on 20 January 2023, after observations were collected over a long enough time span to confirm the satellite’s orbit.<ref name=”MPEC-2023-B51″/> The satellite has a diameter of about {{cvt|2|km|mi}} for an [[absolute magnitude#Solar System bodies (H)|absolute magnitude]] of 16.7.<ref name=”SheppardMoons”/> |
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S/2018 J 4 is an [[irregular moon]] of Jupiter on an highly [[orbital inclination|inclined]] [[retrograde orbit|prograde]] orbit at an angle of 53° with respect to the [[ecliptic]] plane. It belongs to the same group as the similarly-inclined moon [[Carpo (moon)|Carpo]], which was long thought to be an outlier until the discovery of S/2018 J 4.<ref name=”SheppardMoons”/> Like all irregular moons of Jupiter, S/2018 J 4’s orbit is highly variable over time due to gravitational [[perturbation (astronomy)|perturbations]] by the Sun and other planets.<ref name=”Brozovic2017″/> On average, S/2018 J 4’s orbit has a [[semi-major axis]] of {{convert|16.3|e6km|e6mi|abbr=unit}}, an [[orbital eccentricity|eccentricity]] of 0.18, and a very high [[orbital inclination|inclination]] of 50° with respect to the [[ecliptic]].<ref name=”jplsats-elem”/> |
S/2018 J 4 is an [[irregular moon]] of Jupiter on an highly [[orbital inclination|inclined]] [[retrograde orbit|prograde]] orbit at an angle of 53° with respect to the [[ecliptic]] plane. It belongs to the same group as the similarly-inclined moon [[Carpo (moon)|Carpo]], which was long thought to be an outlier until the discovery of S/2018 J 4.<ref name=”SheppardMoons”/> Like all irregular moons of Jupiter, S/2018 J 4’s orbit is highly variable over time due to gravitational [[perturbation (astronomy)|perturbations]] by the Sun and other planets.<ref name=”Brozovic2017″/> On average, S/2018 J 4’s orbit has a [[semi-major axis]] of {{convert|16.3|e6km|e6mi|abbr=unit}}, an [[orbital eccentricity|eccentricity]] of 0.18, and a very high [[orbital inclination|inclination]] of 50° with respect to the [[ecliptic]].<ref name=”jplsats-elem”/> |
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Latest revision as of 01:33, 9 February 2026
Outer moon of Jupiter
S/2018 J 4 is a small outer natural satellite of Jupiter discovered by Scott S. Sheppard on 11 May 2018, using the 4.0-meter VÃctor M. Blanco Telescope at Cerro Tololo Observatory, Chile. It was announced by the Minor Planet Center on 20 January 2023, after observations were collected over a long enough time span to confirm the satellite’s orbit.[1] The satellite has a diameter of about 2Â km (1.2Â mi) for an absolute magnitude of 16.7.[4]
S/2018 J 4 is an irregular moon of Jupiter on an highly inclined prograde orbit at an angle of 53° with respect to the ecliptic plane. It belongs to the same group as the similarly-inclined moon Carpo, which was long thought to be an outlier until the discovery of S/2018 J 4.[4] Like all irregular moons of Jupiter, S/2018 J 4’s orbit is highly variable over time due to gravitational perturbations by the Sun and other planets.[5] On average, S/2018 J 4’s orbit has a semi-major axis of 16.3 million km (10.1 million mi), an eccentricity of 0.18, and a very high inclination of 50° with respect to the ecliptic.[3]
Like Carpo, S/2018 J 4’s very high inclination subjects it to the Lidov–Kozai resonance, where there is a periodic exchange between its orbital eccentricity and inclination while its argument of pericenter oscillates about a constant value without apsidally precessing.[6] For example, the Lidov–Kozai resonance causes Carpo’s eccentricity and inclination to fluctuate between 0.19–0.69 and 44–59°, respectively.[5] S/2018 J 4’s argument of pericenter oscillates about 270° with respect to the ecliptic, which keeps its perijove always above Jupiter and apojove below Jupiter.[3]
