Mizuho orbits the Sun in the outer main-belt at a distance of 2.7–3.5 AU once every 5 years and 5 months (1,967 days). Its orbit has an eccentricity of 0.13 and an inclination of 12° with respect to the ecliptic.
In February 2010, a rotational lightcurve for Mizuho was obtained from photometric observations by James W. Brinsfield at the Via Capote Observatory (G69) in California. It gave a rotation period of 5.47 hours with a brightness variation of 0.30 magnitude (U=2+).
Diameter and albedo
According to the surveys carried out by the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Mizuho measures between 18.0 and 18.9 kilometers in diameter and its surface has an albedo of between 0.207 and 0.219, which is typical for stony asteroids. The Collaborative Asteroid Lightcurve Link, however assumes a standard albedo for a carbonaceous C-type asteroid of 0.057 and correspondingly calculates a much larger diameter of 35.3 kilometers.
The discoverer named this minor planet after his daughter, Mizuho Urata. It was the first asteroid in over 50 years to be discovered by a non-professional astronomer, which set off a wave of interest in amateur asteroid discovery, especially in Japan. The official naming citation was published by the Minor Planet Center before November 1977 (M.P.C. 4482).