Key Facts

  • Classified as a Apollo-class Asteroid
  • Comparable in size to the San Francisco Bay (6.25 km diameter)
  • Will pass within 12,353,047 km of Earth in 2050
  • Classified as a Near Earth Asteroid (NEA)
  • Classified as a Potentially Hazardous Asteroid (PHA)
  • See orbit simulation


Phaethon is a small asteroid whose orbit crosses the orbit of Earth. NASA JPL has classified Phaethon as a "Potentially Hazardous Asteroid" due to its predicted close pass(es) with Earth.

Phaethon orbits the sun every 524 days (1.43 years), coming as close as 0.14 AU and reaching as far as 2.40 AU from the sun. Its orbit is highly elliptical. Phaethon is about 6.3 kilometers in diameter, making it larger than most asteroids, comparable in size to the San Francisco Bay.

The rotation of Phaethon has been observed. It completes a rotation on its axis every 3.60 days.

Phaethon's spectral type F (Tholen) / B (SMASSII) indicates that it is likely to contain iron, hydrogen, ammonia, and nitrogen.

Close Approaches

Phaethon's orbit is 0.02 AU from Earth's orbit at its closest point. This means that there is an wide berth between this asteroid and Earth at all times.

Phaethon has 9 close approaches predicted in the coming decades:

Date Distance from Earth (km) Velocity (km/s)
Dec. 11, 2050 12,353,047 36.236
Dec. 18, 2060 16,624,269 30.648
Dec. 14, 2093 2,965,102 34.235
Dec. 22, 2103 25,661,646 29.015
Dec. 13, 2136 8,237,421 35.401
Dec. 19, 2146 13,502,056 31.170
Dec. 9, 2179 28,507,597 39.646
Dec. 15, 2189 5,308,323 34.795
Dec. 20, 2199 14,196,277 31.016

Images and Observations

Phaethon's orbit is determined by observations dating back to Oct. 27, 1983. It was last officially observed on July 25, 2019. The IAU Minor Planet Center records 4,183 observations used to determine its orbit.

Accessibility and Exploration

This asteroid is not considered a viable target for human exploration by the NHATS study.

Similar Objects

These objects have orbits that share similar characteristics to the orbit of Phaethon:



   or view a random object

Orbital Elements

  • Epoch: 2458600.5 JD
  • Semi-major axis: 1.27137281191 AU
  • Eccentricity: 0.889897654918
  • Inclination: 22.2602446129°
  • Longitude of Ascending Node: 265.216234901°
  • Argument of Periapsis: 322.185510547°
  • Mean Anomaly: 313.938975878°

Physical Characteristics

  • Diameter: 6.25000 km
  • Magnitude: 14.6
  • Albedo: 0.1066
  • Spectral type (Tholen): F
  • Spectral type (SMASS): B

Derived Characteristics

  • Orbit Period: 524 days (1.43 years)
  • Avg. Orbit Speed: 26.42 km/s
  • Aphelion Distance: 2.40 AU
  • Perihelion Distance: 0.14 AU
  • Rotation Period: 3.60 days
  • Approx. Composition: iron, hydrogen, ammonia, and nitrogen.

Size Comparison

Orbit Simulation

Sky Map

The position of Phaethon is indicated by a ◯ pink circle. Note that the object may not be in your current field of view. Use the controls below to adjust position, location, and time.