# 246 Asporina
**246 Asporina** (provisional designation A885EA) is a main-belt asteroid about 51 km across, discovered on 1885-03-08 by A. Borrelly at [Marseille](https://www.edgepedia.org/marseille)[1](https://www.lpi.usra.edu/resources/asteroids/asteroid/?asteroid_id=A885EA). It is one of the comparatively rare A-type asteroids, a class defined by spectra dominated by the mineral olivine, and it has served as a reference object for studies of differentiated planetesimals[2](https://ntrs.nasa.gov/citations/20050175725).
| Key fact | Detail |
|---|---|
| Designation and discovery | Number 246, provisional A885EA; discovered 1885-03-08 by Borrelly, A. at Marseille[1](https://www.lpi.usra.edu/resources/asteroids/asteroid/?asteroid_id=A885EA) |
| Class | Main-belt asteroid (MBA); A-type, olivine-dominated spectrum[1](https://www.lpi.usra.edu/resources/asteroids/asteroid/?asteroid_id=A885EA) • [3](https://academic.oup.com/mnras/article/477/2/2786/4937819) |
| Size | Diameter 50.891 km; about 60 km in a 2007 occultation prediction[1](https://www.lpi.usra.edu/resources/asteroids/asteroid/?asteroid_id=A885EA) • [4](https://www.occultations.org.nz/planet/2007/updates/071127_246_9245_u.htm) |
| Rotation | 16.222 h (catalog value); 16.234 h from 2009 photometry with 433 data points[1](https://www.lpi.usra.edu/resources/asteroids/asteroid/?asteroid_id=A885EA) • [5](https://mpbulletin.org/issues/MPB_38-4.pdf) |
| Orbit | Semi-major axis 2.695 au, eccentricity 0.1088, inclination 15.6216 degrees[1](https://www.lpi.usra.edu/resources/asteroids/asteroid/?asteroid_id=A885EA) |
| Reflectivity | Geometric albedo 0.193[1](https://www.lpi.usra.edu/resources/asteroids/asteroid/?asteroid_id=A885EA) |
| Meteorite link | Best spectral analog for the angrite meteorites among 712 asteroids compared[6](https://www.sciencedirect.com/science/article/pii/S0019103524004895) |
## Orbit and physical properties
Asporina orbits in the main asteroid belt at a semi-major axis of 2.695 au with eccentricity 0.1088 and an inclination of 15.6216 degrees to the ecliptic[1](https://www.lpi.usra.edu/resources/asteroids/asteroid/?asteroid_id=A885EA). Its cataloged diameter is 50.891 km and its geometric albedo is 0.193, a moderately bright surface for an asteroid[1](https://www.lpi.usra.edu/resources/asteroids/asteroid/?asteroid_id=A885EA). A stellar occultation prediction for 2007 used a diameter of about 60 km[4](https://www.occultations.org.nz/planet/2007/updates/071127_246_9245_u.htm).
The rotation period is long for a main-belt object. A 2009 lightcurve campaign over 2009-04-23 to 2009-04-29, using 433 data points at phase angles of 14.7 to 16.6 degrees, gave a period of 16.234 h with an uncertainty of 0.001 h[5](https://mpbulletin.org/issues/MPB_38-4.pdf); the cataloged value is 16.222 h[1](https://www.lpi.usra.edu/resources/asteroids/asteroid/?asteroid_id=A885EA).
## The A-type class and olivine
A-type asteroids are a rare taxonomic class; a 2005 review counted no more than 17 known objects at that time, and later surveys such as SMASS and SMASS II added 12 new members to the original five[2](https://ntrs.nasa.gov/citations/20050175725). The class is defined by moderately high albedos (0.13 to 0.39), extremely reddish slopes shortward of 0.7 micrometers, and a strong absorption feature centered near 1.05 micrometers[2](https://ntrs.nasa.gov/citations/20050175725). In the Bus and Binzel definition, A-types show a very steep to extremely steep ultraviolet slope shortward of 0.75 micrometers and a moderately deep absorption feature longward of 0.75 micrometers[3](https://academic.oup.com/mnras/article/477/2/2786/4937819).
The absorption band is the signature of olivine. High-resolution infrared spectra in the 0.8 to 2.6 micrometer region published for 246 Asporina, [289 Nenetta](https://www.edgepedia.org/289-nenetta), and [446 Aeternitas](https://www.edgepedia.org/446-aeternitas) all show the distinctive deep multiple absorption band of olivine near 1.1 micrometers, with an overall continuum slope suggesting a metal component; this interpretation makes A-type asteroids potential parent bodies of pallasites, the stony-iron meteorites composed of olivine crystals in metallic nickel-iron[7](https://www.lpi.usra.edu/lpi/contribution_docs/LPI-000537.pdf). Asporina is a standard member of the class in later work: one survey of olivine-rich near-Earth asteroids lists it among six A-type objects alongside (289) Nenetta, (446) Aeternitas, (863) Benkoela, (1951) Lick, and (2501) Lohja[3](https://academic.oup.com/mnras/article/477/2/2786/4937819), and spectroscopic studies of olivine-dominated asteroids regularly include it[8](https://www.boulder.swri.edu/~bottke/Reprints/Sanchez_2014_Icarus_228_288_Olivine_Asteroids.pdf).
## Meteorite connections
In 2024, researchers who matched the ultraviolet-visible-near-infrared spectra of ten angrite meteorites against those of 712 asteroids determined that (246) Asporina is the closest spectral match to the angrites, and suggested it may be a piece of a Moon- to Mars-sized parent body that formerly occupied the inner [Solar System](https://www.edgepedia.org/solar-system) before being built into the terrestrial planets as they formed.[6](https://www.sciencedirect.com/science/article/pii/S0019103524004895) Angrites are a rare group of igneous meteorites, so a main-belt spectral match is a clue to where such differentiated material survives today.
## Observational record
Asporina is bright enough for targeted campaigns. It was observed by radar on 2014-05-28, when a Doppler-only continuous-wave echo power spectrum was obtained at 20 Hz frequency resolution; the polarization ratio on that date was 0.32[1](https://www.lpi.usra.edu/resources/asteroids/asteroid/?asteroid_id=A885EA). Stellar occultations also probe its size and shape: on 2007 Nov 27 UT the asteroid occulted a magnitude 10.1 star in Orion along a path across New Zealand's North Island passing near Auckland and Whangarei[4](https://www.occultations.org.nz/planet/2007/updates/071127_246_9245_u.htm), and further occultation events have been predicted since[9](https://astro.kretlow.de/cora/events/sodis/2025-12-31/UCAC4%20466-035942/%28246%29%20Asporina/). Its spectral behavior has also been examined against Gaia reflectance spectra, with marked differences noted between Gaia and ground-based spectra of Asporina, a caution for taxonomy built on different observing conditions[10](https://www.aanda.org/articles/aa/pdf/2023/06/aa43791-22.pdf).
## References
1. [LPI Asteroids: 246 Asporina (A885EA)](https://www.lpi.usra.edu/resources/asteroids/asteroid/?asteroid_id=A885EA)
2. [Reddy, V., Hardersen, P. S., Gaffey, M. J., Abell, P. A. (2005). Mineralogy and Temperature-induced Spectral Investigations of A-type Asteroids 246 Asporina and 446 Aeternitas. Lunar and Planetary Science XXXVI.](https://ntrs.nasa.gov/citations/20050175725)
3. [de León et al. (2018). Olivine-rich asteroids in the near-Earth space. Monthly Notices of the Royal Astronomical Society 477, 2786.](https://academic.oup.com/mnras/article/477/2/2786/4937819)
4. [RASNZ Occultation Section: Asporina Occultation Update, 2007 Nov 27](https://www.occultations.org.nz/planet/2007/updates/071127_246_9245_u.htm)
5. [Minor Planet Bulletin 38 (2011): 246 Asporina lightcurve, 2009 observations](https://mpbulletin.org/issues/MPB_38-4.pdf)
6. [Remnants of a lost Planetesimal: Searching for the Angrite parent body. Icarus (2024).](https://www.sciencedirect.com/science/article/pii/S0019103524004895)
7. [Bell, J. F., Gaffey, M. J., Hawke, B. R. Spectroscopic Identification of Probable Pallasite Parent Bodies. LPI Contributions.](https://www.lpi.usra.edu/lpi/contribution_docs/LPI-000537.pdf)
8. [Sanchez et al. (2014). Olivine-dominated asteroids in the main belt. Icarus 228, 288-300.](https://www.boulder.swri.edu/~bottke/Reprints/Sanchez_2014_Icarus_228_288_Olivine_Asteroids.pdf)
9. [CORA: 2025-12-31 occultation by (246) Asporina](https://astro.kretlow.de/cora/events/sodis/2025-12-31/UCAC4%20466-035942/%28246%29%20Asporina/)
10. [Mahlke et al. (2023). Asteroid taxonomy from cluster analysis of spectrometry and albedo. A&A 674, A35.](https://www.aanda.org/articles/aa/pdf/2023/06/aa43791-22.pdf)
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*Topic: Encyclopedia › Places and geography › Extraterrestrial places › Small bodies of the Solar System › Main-belt asteroids and numbered minor planets › Middle-belt asteroids › Asteroids named for mythological figures*
*Initially written Oct 21, 2026*
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