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 "title": "5258 Rhoeo",
 "updated": "2026-10-25",
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 "excerpt": "5258 Rhoeo is a large Jupiter trojan asteroid about 53 kilometers in diameter, discovered by Japanese astronomer Yoshiaki Oshima on 1 January 1989 and named after Rhoeo of Greek myth.",
 "snippet": "5258 Rhoeo is a large Jupiter trojan asteroid about 53 kilometers in diameter, discovered by Japanese astronomer Yoshiaki Oshima on 1 January 1989 and named after Rhoeo of Greek myth.",
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 "markdown": "# 5258 Rhoeo\n\n**5258 Rhoeo** (provisional designation 1989 AU₁) is a large [Jupiter trojan](https://www.edgepedia.org/jupiter-trojan) asteroid, approximately 53 kilometers in diameter, that shares Jupiter's orbit around the Sun in the leading L4 swarm, the so-called Greek camp. Japanese astronomer Yoshiaki Oshima found the asteroid on 1 January 1989 at the Gekko Observatory, located east of Shizuoka, Japan; its name honors Rhoeo of Greek myth, Apollo's beloved and the mother of their son Anius.<sup>[1](https://www.wgsbn-iau.org/files/Bulletins/V001/WGSBNBull_V001_001.pdf)</sup>\n|---|---|\n| Family status | Identified as a very likely interloper in the Eurybates family by a 2022 dynamical study<sup>[2](https://www2.boulder.swri.edu/~bottke/Reprints/Marschall_2022_AJ_164_167_Trojans_Strength.pdf)</sup> |\n\n## Orbit and Trojan setting\n\nJupiter trojans are bodies trapped in a 1:1 mean-motion resonance with Jupiter, librating around the stable L4 and L5 Lagrange points located 60 degrees ahead of and behind the planet. By convention, L4 asteroids are named for Greek characters of the [Trojan War](https://www.edgepedia.org/trojan-war) and L5 asteroids for characters on the Trojan side, so the two swarms are called the Greek camp and the Trojan camp.<sup>[3](https://www.nasa.gov/missions/how-were-the-trojan-asteroids-discovered-and-named/)</sup>\n\nIts orbit never brings it near Earth; JPL's [Center for Near-Earth Object Studies](https://www.edgepedia.org/center-for-near-earth-object-studies) shows no close approaches, and the asteroid is classified neither as a near-Earth object nor as potentially hazardous.<sup>[4](https://www.spacereference.org/asteroid/5258-rhoeo-1989-au1)</sup>\n\n## Physical characteristics\n\nRhoeo rotates slowly, completing one turn in 19.85 ± 0.05 hours. Slow rotation is a recognized feature of the Trojan population, which shows a substantial excess of slow rotators compared with main-belt asteroids and appears to lack fast-spinning objects above a spin barrier between 4 and 4.8 hours.<sup>[5](https://doi.org/10.1007/s11214-024-01052-7)</sup>\n\n## Membership in the Eurybates family\n\nA 2022 study by Raphael Marschall, David Nesvorný, and colleagues in *The Astronomical Journal* examined the family and concluded that Rhoeo is a very likely interloper rather than a true fragment of the family-forming impact. As the second brightest and largest object identified by the hierarchical clustering method, it is clearly displaced in proper eccentricity and inclination relative to the family center; a fragment that large would not be expected to be ejected at such high speed, since collisional families typically place their largest members near the center of the orbital element distribution. Rhoeo's anomalous color compared with other family members strengthens this conclusion.<sup>[2](https://www2.boulder.swri.edu/~bottke/Reprints/Marschall_2022_AJ_164_167_Trojans_Strength.pdf)</sup>\n\n## Name\n\nThe Minor Planet was named after Rhoeo of Greek mythology. According to the naming citation, Rhoeo was thrown into the ocean locked in a chest after her father learned she was pregnant; she was guided by Apollo, her lover, to the island of Delos, where she gave birth to Anius.<sup>[1](https://www.wgsbn-iau.org/files/Bulletins/V001/WGSBNBull_V001_001.pdf)</sup>\n\n## References\n\n1. [WGSBN Bulletin 1, #1, Working Group Small Body Nomenclature, IAU](https://www.wgsbn-iau.org/files/Bulletins/V001/WGSBNBull_V001_001.pdf)\n2. [Marschall et al. (2022). The Astronomical Journal, 164, 167](https://www2.boulder.swri.edu/~bottke/Reprints/Marschall_2022_AJ_164_167_Trojans_Strength.pdf)\n3. [How Were the Trojan Asteroids Discovered and Named? NASA](https://www.nasa.gov/missions/how-were-the-trojan-asteroids-discovered-and-named/)\n4. [Asteroid Rhoeo, Space Reference](https://www.spacereference.org/asteroid/5258-rhoeo-1989-au1)\n5. [Mottola et al. (2024). Shapes, Rotations, Photometric and Internal Properties of Jupiter Trojans. Space Science Reviews, 220, 17](https://doi.org/10.1007/s11214-024-01052-7)\n\n---\n*Topic: Encyclopedia › Places and geography › Extraterrestrial places › Small bodies of the Solar System › Jupiter Trojans and other dynamical groups › Greek-camp Jupiter Trojans › Women and consorts of Greek myth*\n\n*Initially written Oct 21, 2026 · Edited: Oct 25, 2026*\n\n*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*\n\nLicense: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license\n",
 "same_as": [
  "https://www2.boulder.swri.edu/~bottke/Reprints/Marschall_2022_AJ_164_167_Trojans_Strength.pdf"
 ],
 "url": "https://www.edgepedia.org/5258-rhoeo",
 "markdown_url": "https://www.edgepedia.org/5258-rhoeo.md",
 "license": {
  "name": "Edgepedia Community License 1.0",
  "url": "https://www.edgepedia.org/edgepedia/license",
  "summary": "Free with credit, commercial use included. AI training is open to everyone. For other uses, organizations over USD 100M in revenue or 100M monthly users license separately.",
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 "credit": "\"5258 Rhoeo\", Edgepedia (EdgeChat), https://www.edgepedia.org/5258-rhoeo. Edgepedia Community License 1.0.",
 "credit_md": "\"[5258 Rhoeo](https://www.edgepedia.org/5258-rhoeo)\", Edgepedia (EdgeChat), [https://www.edgepedia.org/5258-rhoeo](https://www.edgepedia.org/5258-rhoeo). [Edgepedia Community License 1.0](https://www.edgepedia.org/edgepedia/license).",
 "credit_html": "\"<a href=\"https://www.edgepedia.org/5258-rhoeo\">5258 Rhoeo</a>\", Edgepedia (EdgeChat), <a href=\"https://www.edgepedia.org/5258-rhoeo\">https://www.edgepedia.org/5258-rhoeo</a>. <a href=\"https://www.edgepedia.org/edgepedia/license\">Edgepedia Community License 1.0</a>.",
 "speakable": "5258 Rhoeo is a large Jupiter trojan asteroid about 53 kilometers in diameter, discovered by Japanese astronomer Yoshiaki Oshima on 1 January 1989 and named after Rhoeo of Greek myth."
}