3200 Phaethon
| Discovery | |
|---|---|
| Discoverer | Simon Green and John K. Davies/IRAS |
| Discovery date | October 11, 1983 |
| Alternative names | 1983 TB |
| Minor planet category | Apollo asteroid, Mercury-crosser asteroid, Venus-crosser asteroid, Mars-crosser asteroid |
| Orbital characteristics Epoch July 14, 2004 (JD 2453200.5) |
|
| Aphelion | 359.456 Gm (2.403 AU) |
| Perihelion | 20.922 Gm (0.140 AU) |
| Semi-major axis | 190.189 Gm (1.271 AU) |
| Eccentricity | 0.890 |
| Orbital period | 523.586 d (1.43 a) |
| Average orbital speed | 19.98 km/s |
| Mean anomaly | 200.798° |
| Inclination | 22.169° |
| Longitude of ascending node | 265.427° |
| Argument of perihelion | 321.978° |
| Physical characteristics | |
| Dimensions | 5.1 km |
| Mass | 1.4×1014 kg |
| Mean density | 2 ? g/cm³ |
| Equatorial surface gravity | 0.0014 m/s² |
| Escape velocity | 0.0027 km/s |
| Rotation period | ? d |
| Albedo | 0.1 ? |
| Temperature | ~247 K |
| Spectral type | B-type asteroid |
| Absolute magnitude | 14.6 |
3200 Phaethon (sometimes incorrectly spelled Phaeton) is an Apollo asteroid and a dead comet.
Simon F. Green and John K. Davies, while searching Infrared Astronomical Satellite (IRAS) data for moving objects, found 3200 Phaethon (1983 TB) in pictures from October 11, 1983. It was announced on October 14 in IAUC 3878 along with optical confirmation by Charles T. Kowal, who reported 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 December 10,2007. It will draw nearer in 2017, 2050, 2060, and closer still on December 14, 2093, passing within 0.0198 AU (3.0 Gm).
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