3873 Roddy
Stony Hungarian asteroid, Mars-crosser, suspected binary system.
3873 Roddy (provisionally known as 1984 WB) is a stony asteroid from the inner edge of the main belt, roughly 7 kilometers wide. It crosses the orbit of Mars and is thought to be a binary system. American astronomer Carolyn Shoemaker discovered it on 21 November 1984 at California’s Palomar Observatory. The asteroid was later named for U.S. astrogeologist David Roddy.
**Orbit and classification** Roddy belongs to the Hungaria family, the tightest cluster of asteroids near the Sun. It travels around the Sun at distances between 1.6 and 2.1 AU, completing one orbit every 2 years and 7 months (951 days). Its path has an eccentricity of 0.13 and is tilted 23° relative to the ecliptic. A precovery image from the same observatory, taken in 1953, pushed the asteroid’s known observation arc back 31 years before its official discovery.
**Physical characteristics** In the SMASS classification, Roddy is a common S-type (stony) asteroid, though it has also been described as a rarer L-type.
**Diameter and albedo** Surveys by NASA’s NEOWISE mission and Japan’s Akari satellite give diameters of 5.0 and 7.5 kilometers, respectively, with exceptionally bright albedos of 0.419 and 0.512. By contrast, the Collaborative Asteroid Lightcurve Link assumes a standard stony albedo of 0.20 and, using an absolute magnitude of 13.1, calculates a diameter of 7.1 kilometers.
**Moon and lightcurve** Astronomer Brian Warner conducted many photometric observations at Colorado’s Palmer Divide Observatory. One of the best lightcurves showed a rotation period of 2.4782 hours and a brightness variation of 0.05 magnitude (quality rating U=3). Other measurements gave similar periods between 2.478 and 2.486 hours. Strong but still uncertain evidence suggests Roddy has a moon. One solution gives the satellite an orbital period of 19.24 ± 0.02 hours and a diameter about 27% that of Roddy (just under 2 km), though an alternative orbital period of 23.8 hours is also possible.
**Naming** The asteroid honors David J. Roddy (1932–2002), an American astrogeologist at the U.S. Geological Survey known for his work on impact craters, mathematical models of impacts, studies of Devonian craters, and field experiments using explosives. The naming citation was published by the Minor Planet Center on 12 December 1989 (M.P.C. 15574).
Quick Facts
- Minorplanet
- yes
- Background
- #FA8072
- Discovered
- 21 November 1984
- Discoverer
- C. Shoemaker
- Discovery Site
- Palomar Obs.
- Mpc Name
- (3873) Roddy
- Named After
- David Roddy / (American astrogeologist)
- Mp Category
- Mars-crosser / Hungaria
- Epoch
- 4 September 2017 (JD 2458000.5)
- Uncertainty
- 0
- Observation Arc
- 32.46 yr (11,855 days)
- Aphelion
- 2.1452 AU
Facts from the source article.
Lore & Background
3873 Roddy is a member of the Hungaria family, which forms the innermost dense concentration of asteroids in the Solar System. It orbits the Sun at a distance of 1.6–2.1 AU once every 2 years and 7 months (951 days), with an eccentricity of 0.13 and an inclination of 23° with respect to the ecliptic. The first precovery was taken at the discovering observatory in 1953, extending the asteroid's observation arc by 31 years prior to its discovery.
In the SMASS classification, Roddy is a common S-type asteroid, but it has also been characterized as a rare L-type asteroid. According to surveys by NASA's NEOWISE mission and the Japanese Akari satellite, the asteroid measures 5.0 and 7.5 kilometers, with an exceptionally high albedo of 0.419 and 0.512, respectively. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 7.1 kilometers with an absolute magnitude of 13.1.
A large number of photometric observations by American astronomer Brian Warner at the Palmer Divide Observatory in Colorado measured the asteroid's lightcurve. One of the best results gave a rotation period of 2.4782 hours and a brightness variation of 0.05 magnitude. While there is strong evidence for an asteroid moon orbiting Roddy, its existence is still uncertain as of 2016. Based on one observation, the satellite has an orbital period of 19.24±0.02 hours and measures about 27% of Roddy's diameter (slightly less than 2 km), though an alternative orbital period of 23.8 hours is also possible.
Reader's Guide
The significance of 3873 Roddy lies in its multiple notable characteristics as described in the source article. As a member of the Hungaria family, it represents the innermost dense concentration of asteroids in the Solar System, and its status as a Mars-crosser adds dynamical interest. The asteroid is particularly notable for its suspected binary nature: while strong evidence exists for a satellite, its existence remains uncertain as of 2016, with two possible orbital periods (19.24 or 23.8 hours) and a secondary body estimated at about 27% of Roddy's diameter. This uncertainty is preserved in the record. Additionally, Roddy's surface has an exceptionally high albedo (0.419–0.512) according to NEOWISE and Akari surveys, which is unusual for a stony asteroid. The asteroid was named after David J. Roddy (1932–2002), an American astrogeologist and authority on terrestrial impact craters at the U.S. Geological Survey, noted for his mathematical models of impact events and field experiments using explosives. The naming citation was published by the Minor Planet Center on 12 December 1989.
Did You Know?
- 3873 Roddy was discovered on 21 November 1984 by American astronomer Carolyn Shoemaker at Palomar Observatory.
- It is a suspected binary system, but the existence of its moon was still uncertain as of 2016.
- The asteroid has an exceptionally high albedo of 0.419 to 0.512, according to NEOWISE and Akari surveys.
- It was named after American astrogeologist David Roddy, known for mathematical models of impact events.
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