[1] The 2017 Earth approach distance of about 10 million km was known with an accuracy of ±700 m.[1] Phaethon was the first asteroid to be discovered using images from a spacecraft.

Simon F. Green and John K. Davies discovered it in images from October 11, 1983, while searching Infrared Astronomical Satellite (IRAS) data for moving objects.

It was formally announced on October 14 in IAUC 3878 along with optical confirmation by Charles T. Kowal, who reported it to be asteroidal in appearance.

Phaethon is a possible candidate for detecting general relativistic and/or solar oblateness effects in its orbital motion due to the frequent close approaches to the Sun.

[11] The Apollo asteroids (155140) 2005 UD and (225416) 1999 YC share similar orbits with Phaethon, suggesting a possible common breakup origin.

[21][22] In 2020, polarimetric study revealed Phaethon has a surface with steep slopes covered by a mix of regolith with larger pebbles.

[24] In 2022 it was shown [25][26] how Phaethon's blue color and its rock-comet-like emission activity can be explained by the effects of the intense solar heating at perihelion causing sublimation of any darkish-red refractory organic, nano-phase iron (nFe0), and pyroxene materials on its surface.

Analysis of a mid-infrared spectral emissivity spectrum from the Spitzer Space Telescope showed Phaethon to be linked to the rare Yamato-type (CY) carbonaceous chondrites.

These minerals decompose at the temperatures that Phaethon reaches at perihelion, resulting in outgassing, in a process called thermal decomposition.