Asteroid 1685, a member of the Apollo group, discovered in 1948 by the American astronomer Carl Alvar Wirtanen (1910–90). It passed within 0.14 au (20.9 million km) of Earth in 1972. Toro is an S-type asteroid about 3–4 km in diameter. Its orbit has a semimajor axis of 1.37 au, period 1.60 years, perihelion 0.77 au, aphelion 1.96 au, and inclination 9°.4; and is remarkable for a resonance involving both Earth and Venus.