3200 Phaethon

3200 Phaethon, sometimes incorrectly spelt Phaeton, is an Apollo asteroid and a dead comet.

3200 Phaethon

Asteroid (3200) Phaethon imaged on 25 Dec 2010 with the 37 cm F14 Cassegrain telescope of Winer Observatory, Sonoita (MPC 857) by Marco Langbroek.
Discovery
Discovery date	11 October 1983
Designations
Named after	Phaëton
Alternative names	1983 TB
Minor planet category	Apollo asteroid
Orbital characteristics
Epoch July 14, 2004 (JD 2453200.5)
Aphelion	2.403 AU (359.456 Gm)
Perihelion	0.140 AU (20.922 Gm)
Semi-major axis	1.271 AU (190.189 Gm)
Eccentricity	0.890
Orbital period	1.43 a (523.586 d)
Average orbital speed	19.98 km/s
Mean anomaly	200.798°
Inclination	22.169°
Physical characteristics
Dimensions	5.1 km
Mass	1.4×1014 kg

It was announced on 14 October 1983 in IAUC 3878, with optical confirmation that it looks like an asteroid. It was the first asteroid to be found by a spacecraft. It measures 5.10 km in diameter.

Phaethon approaches the Sun closer than any other numbered asteroid. Its perihelion (closest approach to the Sun) is only 0.140 AU – less than half Mercury's perihelion distance. It is a Mercury-, Venus-, Earth- and Mars-crosser. The surface temperature at perihelion could reach ~1025 K, or 1400 F. For this reason, it was named after the Greek myth of Phaëton, son of the sun god Helios.

Phaethon approached to 18.1 Gm on 10 December 2007. It will draw nearer in 2017, 2050, 2060, and closer still on 14 December 2093, passing within 0.0198 AU (3.0  Gm).