3905

3905 is the provisional designation of a minor planet located in the main asteroid belt between Mars and Jupiter. It was discovered on 18 January 1985 by the Japanese astronomer Takao Kuroda at the Kitt Peak National Observatory. The object was later assigned the permanent number 3905 once its orbit was well determined. Its orbital elements are typical of the inner part of the belt, with a semi‑major axis of about 2.7 astronomical units, an eccentricity of 0.15, and an inclination of roughly 5 degrees relative to the ecliptic.

Observations indicate that 3905 has a stony (S‑type) composition, placing it among the common stony asteroids that dominate the inner belt. Photometric studies reveal a rotation period of about 7 hours and a light‑curve amplitude suggesting a moderately elongated shape. Its absolute magnitude is 12.5, which, assuming a typical albedo of 0.20 for stony bodies, implies a diameter near 6 kilometers.

The asteroid has not been assigned a formal name; it remains identified only by its number and provisional designation. It is occasionally cited in catalogues of minor planets and used as a reference point in dynamical studies of the inner asteroid belt, helping astronomers understand collisional evolution and resonant interactions within the population.