Asteroid 3200, a member of the Apollo group, discovered in 1983 by the Infrared Astronomical Satellite. Phaethon's orbit is very similar to that of the Geminid meteor shower, and it may be their parent body. Before the discovery of Phaethon, meteor showers were generally believed to be associated only with comets, but infrared observations suggest that Phaethon has a rocky surface, not the dusty crust expected for an extinct cometary nucleus. Phaethon is an F-class asteroid with a diameter of 5.1 km. Its orbit has a semimajor axis of 1.271 AU, period 1.43 years, perihelion 0.14 AU, aphelion 2.40 AU, and inclination 22°.2. It can approach to within 0.02 AU (3 million km) of the Earth's orbit.
Subjects: Astronomy and Astrophysics.