2815 Soma
Binary Florian asteroid named for the Soma cube puzzle.
2815 Soma, originally designated 1982 RL, is a binary asteroid belonging to the Flora family in the inner main belt. It measures roughly 7 kilometers across and was discovered on 15 September 1982 by American astronomer Edward Bowell at Lowell Observatory’s Anderson Mesa Station in Flagstaff, Arizona. The asteroid is named after the Soma cube, a mechanical puzzle.
Soma orbits the Sun at a distance of 1.9 to 2.6 AU, completing one revolution every 3 years and 4 months (1,219 days). Its orbit has an eccentricity of 0.17 and an inclination of 6° relative to the ecliptic. The object was first observed as 1955 MH at Goethe Link Observatory in 1955, and its observation arc began with 1970 AC at Crimea-Nauchnij, 12 years before its official discovery.
NASA’s WISE survey, with its NEOWISE mission, measured Soma’s diameter at 6.641 and 7.158 kilometers, with corresponding albedos of 0.365 and 0.3207. The Collaborative Asteroid Lightcurve Link, using revised WISE data from Peter Pravec, reports an albedo of 0.2273, a diameter of 7.067 kilometers, and an absolute magnitude of 12.98.
In November 2009, photometric observations by Petr Pravec, Donald Pray, and Peter Kušnirák at Carbuncle Hill Observatory and Ondřejov Observatory produced a lightcurve with a rotation period of 2.7327 hours and a brightness variation of 0.08 magnitude, suggesting a nearly spheroidal shape. The spin rate falls within the typical 2.2-to-20-hour range for most asteroids.
In March 2011, further photometry revealed that Soma is a synchronous binary asteroid, with a moon orbiting every 17.915 hours. The secondary-to-primary mean-diameter ratio is 0.25, giving the satellite a diameter of about 1.75 kilometers. The refined rotation period for the primary is 2.73325 hours with an amplitude of 0.07 magnitude. The system has an absolute magnitude of 12.53 and a phase slope parameter (G) of 0.27.
The minor planet was named for the Soma cube, a dissection puzzle with seven pieces invented by Danish mathematician Piet Hein and popularized by American writer Martin Gardner. The naming citation, proposed by Belgian astronomer Jean Meeus, was published by the Minor Planet Center on 10 September 1984 (M.P.C. 9080).
Quick Facts
- Minorplanet
- yes
- Background
- #D6D6D6
- Discovered
- 15 September 1982
- Discoverer
- E. Bowell
- Discovery Site
- Anderson Mesa Stn.
- Mpc Name
- (2815) Soma
- Pronounced
- ' · s · ou · m · @
- Named After
- Soma cube / (mechanical puzzle)
- Mp Category
- main-beltFlora
- Epoch
- 4 September 2017 (JD 2458000.5)
- Uncertainty
- 0
- Observation Arc
- 61.77 yr (22,562 days)
Facts from the source article.
Lore & Background
2815 Soma is a member of the Flora family, a large family of stony asteroids. It orbits the Sun in the inner main-belt at a distance of 1.9–2.6 AU once every 3 years and 4 months (1,219 days). Its orbit has an eccentricity of 0.17 and an inclination of 6° with respect to the ecliptic. It was first identified as 1955 MH at Goethe Link Observatory in 1955, and its observation arc begins with 1970 AC at Crimea-Nauchnij, 12 years prior to its official discovery at Anderson Mesa.
In November 2009, a rotational lightcurve of Soma was obtained from photometric observations by astronomers Petr Pravec, Donald Pray and Peter Kušnirák at Carbuncle Hill Observatory, Rhode Island, and Ondřejov Observatory, in the Czech Republic. Lightcurve analysis gave a rotation period of 2.7327 hours with a brightness variation of 0.08 magnitude, indicating a nearly spheroidal shape. In March 2011, photometric observations revealed that Soma is a synchronous binary asteroid with a minor-planet moon orbiting it every 17.915 hours. The satellite's diameter is approximately 25% of that of the primary, translating to about 1.75 kilometers. The refined rotation period for the primary is 2.73325 hours.
According to the WISE/NEOWISE survey, Soma measures 6.641 and 7.158 kilometers in diameter with albedos of 0.365 and 0.3207, respectively. The Collaborative Asteroid Lightcurve Link adopts Peter Pravec's revised WISE-data, giving an albedo of 0.2273 and a diameter of 7.067 kilometers with an absolute magnitude of 12.98. The system has an absolute magnitude of 12.53 and a phase slope parameter (G) of 0.27.
Reader's Guide
2815 Soma's significance lies in its binary nature and its connection to recreational mathematics. Discovered in 1982 by Edward Bowell, it was named for the Soma cube, a dissection puzzle invented by Danish mathematician Piet Hein and popularized by American writer Martin Gardner, following a proposal by Belgian astronomer Jean Meeus. The naming citation was published by the Minor Planet Center on 10 September 1984. As a binary asteroid, Soma provides insights into the formation and dynamics of asteroid systems in the inner main belt. Its moon, discovered in 2011, orbits synchronously every 17.915 hours, and the primary's rotation period of 2.73325 hours is within the typical range for most asteroids. The body's nearly spheroidal shape, indicated by a low lightcurve amplitude, and its membership in the Flora family contribute to understanding the physical properties of stony asteroids. The multiple diameter and albedo measurements from WISE/NEOWISE and Pravec's revision highlight the ongoing refinement of asteroid characterization.
Did You Know?
- 2815 Soma is a binary asteroid with a moon that orbits every 17.915 hours.
- The asteroid is named for the Soma cube, a mechanical puzzle invented by Piet Hein.
- Its rotation period was refined to 2.73325 hours from photometric observations in 2011.
More in Notable Asteroids, Part 2 1-24
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