1490 Limpopo, provisional designation 1936 LB, is an asteroid from the inner regions of the asteroid belt, approximately 18 kilometers in diameter. It was discovered on 14 June 1936, by English-born South African astronomer Cyril Jackson at Johannesburg Observatory in South Africa.
Limpopo orbits the Sun at a distance of 2.0–2.7 AU once every 3 years and 7 months (1,318 days). Its orbit has an eccentricity of 0.16 and an inclination of 10° with respect to the ecliptic. The body's observation arc begins 2 weeks prior to its official discovery observation. Its first identification as 1931 BL at Lowell Observatory in 1931 remains unused.
Between August and November 2005, three rotational light-curves of Limpopo were obtained from photometric observations by French amateur astronomer Laurent Bernasconi, Pedro Sada at the Mexican Monterrey Observatory, and Dicy Saylor at University of Georgia, United States. The light-curves gave a rotation period between 6.15 and 6.647 hours with a brightness variation of 0.15–0.26 magnitude (U=2-/3/3).
According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Limpopo measures between 14.84 and 20.21 kilometers in diameter and its surface has an albedo between 0.068 and 0.105. The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0742 and a diameter of 18.55 kilometers based on an absolute magnitude of 12.1. The X-type asteroid is also classified as a metallic M-type by WISE and as a carbonaceous intermediate Xc-type in the SMASS taxonomy.
The minor planet was named after the Limpopo River, which rises in central southern Africa, and flows through Botswana, Mozambique, South Africa and Zimbabwe into the Indian Ocean. Naming citation was published before November 1977 (M.P.C. 909).