1428 Mombasa darker P-type asteroid. 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, "Mombasa" measures between 52.46 and 62.45 kilometers in diameter, ignoring a preliminary result of 127 km, and its surface has an albedo of 0.025 and 0.06. The "Collaborative Asteroid Lightcurve Link" derives an albedo of 0.0415 and a diameter of 56.83 kilometers with an absolute magnitude of 10.3. This minor planet was named after Mombasa, chief-port and second largest city of Kenya on the coast of East Africa. Naming citation
1428 Mombasa years prior to its official discovery at Johannesburg. American astronomer Robert Stephens obtained a rotational lightcurve of "Mombasa" in June 2012. Light-curve analysis gave a rotation period of 16.67 hours with a brightness variation of 0.16 magnitude (). Previous lightcurves were obtained by French amateur astronomer René Roy in February 2006 (17.6 hours, Δ0.15 mag; ), as well as by Scot Hawkins and Richard Ditteon at Oakley Observatory in May 2007 (17.12 hours, Δ0.25 mag; ). On the SMASS taxonomic scheme, "Mombasa" is a , an intermediate between the carbonaceous C and X-type, while it is also described as a