# 528 Rezia
**528 Rezia** (provisional designation 1904 NS) is a large asteroid in the outer main asteroid belt, about 92 km across, discovered on 20 March 1904 by Max F. Wolf at [Heidelberg](https://www.edgepedia.org/heidelberg)[1](https://planety.astro.cz/planetka-528) • [2](https://www.spacereference.org/asteroid/528-rezia-a904-fa). It is named for Rezia, a character in the opera *Oberon* by the German composer [Carl Maria von Weber](https://www.edgepedia.org/carl-maria-von-weber) (1786–1826)[3](https://ndl.ethernet.edu.et/bitstream/123456789/32939/1/Lutz%20D.%20Schmadel.pdf).
| Key fact | Detail |
|---|---|
| Discovery | 20 March 1904 by M. F. Wolf at Heidelberg; provisional designation 1904 NS[1](https://planety.astro.cz/planetka-528) |
| Orbit | Semi-major axis 3.398 AU, eccentricity 0.022, inclination 12.71°; period 2,290 days (6.27 years)[2](https://www.spacereference.org/asteroid/528-rezia-a904-fa) |
| Distance range | Perihelion 3.32 AU, aphelion 3.47 AU[2](https://www.spacereference.org/asteroid/528-rezia-a904-fa) |
| Size | About 92 km diameter (91.966 km); occultation dimensions 83 ±3, 85 ±1, and 87 ±8 km[2](https://www.spacereference.org/asteroid/528-rezia-a904-fa) • [4](https://www.asteroidoccultation.com/observations/Asteroid_Dimensions_from_Occultations.html) |
| Surface brightness | Albedo 0.046, a very dark surface; absolute magnitude H = 9.22[2](https://www.spacereference.org/asteroid/528-rezia-a904-fa) • [1](https://planety.astro.cz/planetka-528) |
| Rotation | 7.34 hours per rotation; spin axis at ecliptic longitude 176°, latitude −59°[2](https://www.spacereference.org/asteroid/528-rezia-a904-fa) • [5](https://vesta.astro.amu.edu.pl/Science/Asteroids/Spindata/spin.pdf) |
| Hazard status | Not a near-Earth object and not classified as potentially hazardous; its orbit stays 2.33 AU from Earth's orbit at the closest point[2](https://www.spacereference.org/asteroid/528-rezia-a904-fa) |
## Orbit and classification
Rezia orbits the Sun in the outer reaches of the main asteroid belt, between Mars and Jupiter[2](https://www.spacereference.org/asteroid/528-rezia-a904-fa). Its orbit is nearly circular, with an eccentricity of 0.022, and tilted 12.71° to the ecliptic; one revolution takes 2,290 days, or about 6.27 years, at an average orbital speed of 16.14 km/s[2](https://www.spacereference.org/asteroid/528-rezia-a904-fa). The orbit carries the asteroid from 3.32 AU at perihelion to 3.47 AU at aphelion[2](https://www.spacereference.org/asteroid/528-rezia-a904-fa).
Because the orbit never approaches Earth's, JPL has not classified Rezia as a potentially hazardous object, and orbital simulations by NASA JPL's CNEOS show no close approaches to Earth[2](https://www.spacereference.org/asteroid/528-rezia-a904-fa). The asteroid is also not considered a viable target for human exploration by the NHATS study[2](https://www.spacereference.org/asteroid/528-rezia-a904-fa).
The orbit is well determined. The IAU Minor Planet Center records 9,550 observations used in the orbit solution, with observations dating back to the discovery date of 20 March 1904[2](https://www.spacereference.org/asteroid/528-rezia-a904-fa). A Czech asteroid database lists 10,592 observations across 56 oppositions covering 1904 to 2026[1](https://planety.astro.cz/planetka-528).
## Physical properties
Rezia is a large body for the main belt, about 92.0 km in diameter, which places it among the larger asteroids of its region[2](https://www.spacereference.org/asteroid/528-rezia-a904-fa). Size estimates from different methods agree closely. The [AKARI](https://www.edgepedia.org/akari) mid-infrared survey measured a diameter of 84.62 ± 1.04 km with an albedo of 0.057[6](https://core.ac.uk/download/pdf/43545172.pdf), while stellar occultation measurements from 2003 to 2017 give dimensions of 83 ±3, 85 ±1, and 87 ±8 km along three axes[4](https://www.asteroidoccultation.com/observations/Asteroid_Dimensions_from_Occultations.html). The albedo of about 0.046 to 0.057 means the surface reflects only around five percent of incident sunlight, a very dark reflectivity typical of many outer-belt asteroids[2](https://www.spacereference.org/asteroid/528-rezia-a904-fa) • [6](https://core.ac.uk/download/pdf/43545172.pdf).
**Rotation and shape.** Rezia completes one rotation every 7.34 hours[2](https://www.spacereference.org/asteroid/528-rezia-a904-fa). A shape and spin model derived by lightcurve inversion, the technique of reconstructing an asteroid's shape and rotation state from its brightness variations, gives a sidereal period of 7.33797 hours and a spin axis pointing at ecliptic longitude 176° and latitude −59°[5](https://vesta.astro.amu.edu.pl/Science/Asteroids/Spindata/spin.pdf) • [7](https://damit.cuni.cz/projects/damit/asteroid_models/index/page%3A295/sort%3Aquality_flag/direction%3Aasc). The model is held in the DAMIT database (Database of Asteroid Models from Inversion Techniques), which collects published asteroid shape models, rotation periods, and spin axis directions[8](https://doi.org/10.1051/0004-6361/200912693).
## Occultations and observing
Stellar occultations, in which the asteroid briefly blocks the light of a background star, have been used to measure Rezia's size and shape. A predicted event on 28 August 2013 was to carry the asteroid's shadow across a path beginning over Brisbane, occulting a 12.2-magnitude star in the constellation [Cetus](https://www.edgepedia.org/cetus-constellation); the combined light of asteroid and star was expected to drop by 2.2 magnitudes for at most 8.9 seconds[9](https://www.occultations.org.nz/planet/2013/updates/130828_528_30096_u.htm). Further occultation chords were recorded in 2023, including events on 8 May and 1 June 2023[10](https://astro.kretlow.de/cora/events/sodis/2023-06-01/UCAC4%20478-052906/%28528%29%20Rezia/).
For amateur observers, Rezia is a accessible target at magnitude around 13.9 near opposition, and in late October 2026 it passes close on the sky to the galaxy NGC 840 in Cetus, a useful alignment for telescope pointing[11](https://minorplanet.info/obsguides/appulses/DSO_October2026.html).
## Name
The name honors Rezia, a character in *Oberon*, an opera by Carl Maria von Weber[3](https://ndl.ethernet.edu.et/bitstream/123456789/32939/1/Lutz%20D.%20Schmadel.pdf). Wolf discovered several other asteroids on the same night in March 1904, including [529 Preziosa](https://www.edgepedia.org/529-preziosa) and, days later, 530 Turandot and [531 Zerlina](https://www.edgepedia.org/531-zerlina), several of which also carry names from opera[3](https://ndl.ethernet.edu.et/bitstream/123456789/32939/1/Lutz%20D.%20Schmadel.pdf).
## References
1. [Planetka Rezia (528), Planety.cz](https://planety.astro.cz/planetka-528)
2. [Asteroid Rezia, Space Reference](https://www.spacereference.org/asteroid/528-rezia-a904-fa)
3. [Dictionary of Minor Planet Names, 5th ed., L. D. Schmadel](https://ndl.ethernet.edu.et/bitstream/123456789/32939/1/Lutz%20D.%20Schmadel.pdf)
4. [Asteroid Dimensions from Occultations, asteroidoccultation.com](https://www.asteroidoccultation.com/observations/Asteroid_Dimensions_from_Occultations.html)
5. [Asteroid spin vector solutions, A. W. Harris et al.](https://vesta.astro.amu.edu.pl/Science/Asteroids/Spindata/spin.pdf)
6. [Mid-Infrared Asteroid Survey with AKARI](https://core.ac.uk/download/pdf/43545172.pdf)
7. [DAMIT asteroid models, (528) Rezia](https://damit.cuni.cz/projects/damit/asteroid_models/index/page%3A295/sort%3Aquality_flag/direction%3Aasc)
8. [DAMIT: a database of asteroid models, Astronomy & Astrophysics](https://doi.org/10.1051/0004-6361/200912693)
9. [Occultation by (528) Rezia, 2013 Aug 28, RASNZ Occultation Section](https://www.occultations.org.nz/planet/2013/updates/130828_528_30096_u.htm)
10. [2023-06-01 occultation by (528) Rezia, Cora Occultation Archive](https://astro.kretlow.de/cora/events/sodis/2023-06-01/UCAC4%20478-052906/%28528%29%20Rezia/)
11. [Asteroid-DSO Appulses, 2026 October, minorplanet.info](https://minorplanet.info/obsguides/appulses/DSO_October2026.html)
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*Topic: Encyclopedia › Places and geography › Extraterrestrial places › Small bodies of the Solar System › Main-belt asteroids and numbered minor planets › Outer-belt asteroids › Asteroids named for literary and allegorical figures*
*Initially written Oct 21, 2026*
*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*
License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license