# 4791 Iphidamas

**4791 Iphidamas** (provisional designation 1988 PB1) is a large Jupiter Trojan asteroid, one of the bodies that share Jupiter's orbit around the Sun. It was discovered on 14 August 1988 and is cataloged by JPL's Small-Body Database, which provides orbital elements, physical parameters, and discovery circumstances for known small bodies<sup>[1](https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html)</sup>.

| Key fact | Detail |
|---|---|
| Classification | Jupiter Trojan; not a near-Earth object and not classified as potentially hazardous<sup>[2](https://www.spacereference.org/asteroid/4791-iphidamas-1988-pb1)</sup> |
| Orbit | Semi-major axis 5.156 AU, eccentricity 0.0461, inclination 25.98 degrees<sup>[2](https://www.spacereference.org/asteroid/4791-iphidamas-1988-pb1)</sup> |
| Period and rotation | Orbital period 4,280 days (11.72 years); rotation period 9.70 hours<sup>[2](https://www.spacereference.org/asteroid/4791-iphidamas-1988-pb1)</sup> |
| Observational record | 2,506 Minor Planet Center observations from 13 August 1988 to 3 July 2023<sup>[2](https://www.spacereference.org/asteroid/4791-iphidamas-1988-pb1)</sup> |

## Orbit

Iphidamas orbits the Sun every 4,280 days, about 11.72 years, on a nearly circular path with eccentricity 0.0461 that carries it from 4.92 AU at perihelion to 5.39 AU at aphelion<sup>[2](https://www.spacereference.org/asteroid/4791-iphidamas-1988-pb1)</sup>. Its orbit is inclined 25.98 degrees to the ecliptic, a relatively steep tilt for a [Trojan](https://www.edgepedia.org/trojan-celestial-body)<sup>[2](https://www.spacereference.org/asteroid/4791-iphidamas-1988-pb1)</sup>. Objects with similar orbital characteristics include 4828 Misenus (1988 RV), [5023 Agapenor](https://www.edgepedia.org/5023-agapenor) (1985 TG3), and [5233 Nastes](https://www.edgepedia.org/5233-nastes) (1988 RL10)<sup>[2](https://www.spacereference.org/asteroid/4791-iphidamas-1988-pb1)</sup>.

The orbit is well determined: the [Minor Planet Center](https://www.edgepedia.org/minor-planet-center) records 2,506 observations spanning from 13 August 1988 to the most recent official observation on 3 July 2023<sup>[2](https://www.spacereference.org/asteroid/4791-iphidamas-1988-pb1)</sup>.

## Physical characteristics

Infrared surveys give consistent size estimates. At roughly 50 to 60 km across, Iphidamas is larger than 99 percent of cataloged asteroids, comparable in size to the U.S. state of [Rhode Island](https://www.edgepedia.org/rhode-island)<sup>[2](https://www.spacereference.org/asteroid/4791-iphidamas-1988-pb1)</sup>.

Its rotation has been observed photometrically: the asteroid completes one turn on its axis every 9.70 hours<sup>[2](https://www.spacereference.org/asteroid/4791-iphidamas-1988-pb1)</sup>. It was among the [Jupiter Trojans](https://www.edgepedia.org/jupiter-trojans) included in a lightcurve survey of 80 objects<sup>[3](https://www.researchgate.net/publication/231138383_Rotational_Properties_of_Jupiter_Trojans_I_Light_Curves_of_80_Objects)</sup>.

## Earth-approach status

Iphidamas's orbit stays at least 3.94 AU from [Earth's orbit](https://www.edgepedia.org/earths-orbit) at their closest points, and orbital simulations by NASA JPL's CNEOS show no close approaches to Earth<sup>[2](https://www.spacereference.org/asteroid/4791-iphidamas-1988-pb1)</sup>. It is accordingly not classified as a potentially hazardous object and is not considered a viable target for human exploration by the NHATS study<sup>[2](https://www.spacereference.org/asteroid/4791-iphidamas-1988-pb1)</sup>.

## References

1. [Small-Body Database Lookup, JPL Solar System Dynamics](https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html)
2. [Asteroid Iphidamas (4791), Space Reference](https://www.spacereference.org/asteroid/4791-iphidamas-1988-pb1)
3. [Rotational Properties of Jupiter Trojans. I. Light Curves of 80 Objects](https://www.researchgate.net/publication/231138383_Rotational_Properties_of_Jupiter_Trojans_I_Light_Curves_of_80_Objects)

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*Topic: Encyclopedia › Places and geography › Extraterrestrial places › Small bodies of the Solar System › Main-belt asteroids and numbered minor planets*

*Initially written Oct 21, 2026 · Edited: Oct 25, 2026*

*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*

License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license