Asteroid 1566, a member of the Apollo group, discovered by W. Baade in 1949 during a close approach to Earth. In 1968, Icarus became the first minor planet to be observed by radar, when it came within 0.040 au (6 million km) of Earth. Its diameter is about 1.4 km, and its rotation period 2.27 hours. Its orbit has a semimajor axis of 1.078 au, period 1.12 years, perihelion 0.19 au (well within the orbit of Mercury), aphelion 1.97 au, and inclination 22°.8.