| Minorplanet: | yes |
| 1881 Shao | |
| Background: |
|
| Discovered: | 3 August 1940 |
| Mpc Name: | (1881) Shao |
| Alt Names: | 1940 PC1968 OO |
| Named After: | Cheng-yuan Shao |
| Epoch: | 23 March 2018 (JD 2458200.5) |
| Uncertainty: | 0 |
| Observation Arc: | 77.71 yr (28,385 d) |
| Perihelion: | 2.8339 AU |
| Semimajor: | 3.1700 AU |
| Eccentricity: | 0.1060 |
| Period: | 5.64 yr (2,062 d) |
| Mean Motion: | / day |
| Inclination: | 9.8706° |
| Asc Node: | 218.07° |
| Arg Peri: | 66.640° |
| Mean Diameter: | |
| Rotation: | |
| Albedo: | |
| Abs Magnitude: | 11.10 11.4 |
1881 Shao, provisional designation or , is a background asteroid from the outer regions of the asteroid belt, approximately 25km (16miles) in diameter. It was discovered on 3 August 1940, by German astronomer Karl Reinmuth at the Heidelberg Observatory in southwest Germany. The presumed C-type asteroid has a rotation period of 7.45 hours. It was named for Chinese astronomer Cheng-yuan Shao.
Shao is a non-family asteroid from the main belt's background population. It orbits the Sun in the outer main-belt at a distance of 2.8–3.5 AU once every 5 years and 8 months (2,062 days; semi-major axis of 3.17 AU). Its orbit has an eccentricity of 0.11 and an inclination of 10° with respect to the ecliptic. The body's observation arc begins with its official discovery observation at Heidelberg in 1940.
Shao is an assumed carbonaceous C-type asteroid.
In July 2013, a rotational lightcurve of Shao was obtained from photometric observations by Italian amateur astronomer Silvano Casulli. Lightcurve analysis gave a rotation period of 7.452 hours with a brightness variation of 0.15 magnitude . A second lightcurve by astronomers at the Palomar Transient Factory from December 2014, gave a shorter period of 5.61 hours and an amplitude of 0.11, indicative for a rather spherical shape.
According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Shao measures between 24.083 and 25.46 kilometers in diameter and its surface has an albedo between 0.0994 and 0.115. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for a carbonaceous asteroid of 0.057, and calculates a diameter of 29.21 kilometers based on an absolute magnitude of 11.4.
This minor planet was named after Chinese astronomer Cheng-yuan Shao (born 1927), an assistant to Richard McCrosky (see previously numbered) in Harvard's minor-planet program at the Harvard–Smithsonian Center for Astrophysics and Oak Ridge Observatory in Massachusetts, United States. Shao was also involved in the recovery of near-Earth asteroid 1862 Apollo. The official was published by the Minor Planet Center on 20 February 1976 .