Key Facts

  • Categorized as a Apollo-class Asteroid
  • Comparable in size to the San Francisco Bay (5.70 km diameter)
  • Will pass within 26,603,572 km of Earth in 2064
  • Classified as a Near Earth Asteroid (NEA)
  • Not a Potentially Hazardous Object
  • See orbit simulation


Hephaistos is a mid-sized asteroid whose orbit crosses the orbit of Earth. NASA JPL has classified Hephaistos as a "Near Earth Asteroid" due to its orbit's proximity to Earth, but it is not considered potentially hazardous because computer simulations have not indicated any imminent likelihood of future collision.

Hephaistos orbits the sun every 1,160 days (3.18 years), coming as close as 0.35 AU and reaching as far as 3.97 AU from the sun. Its orbit is highly elliptical. Hephaistos is about 5.7 kilometers in diameter, making it larger than 99% of asteroids, comparable in size to the San Francisco Bay.

The rotation of Hephaistos has been observed. It completes a rotation on its axis every 48.00 hours.

Close Approaches

Hephaistos's orbit is 0.12 AU from Earth's orbit at its closest point. This means that there is a wide berth between this asteroid and Earth at all times.

Hephaistos has 7 close approaches predicted in the coming decades:

Date Distance from Earth (km) Velocity (km/s)
Sept. 23, 2064 26,603,572 33.859
Jan. 21, 2074 29,574,306 31.827
Sept. 19, 2115 13,376,989 30.322
Jan. 24, 2125 25,352,389 30.487
Sept. 10, 2131 29,506,533 24.055
Sept. 23, 2166 17,689,882 32.232
Jan. 28, 2176 22,629,429 28.803

Images and Observations

Hephaistos's orbit is determined by observations dating back to Sept. 27, 1978. It was last officially observed on Aug. 5, 2023. The IAU Minor Planet Center records 3,471 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 Hephaistos:



   or view a random object

Orbital Elements

  • Epoch: 2460200.5 JD
  • Semi-major axis: 2.161 AU
  • Eccentricity: 0.8374
  • Inclination: 11.54°
  • Longitude of Ascending Node: 27.5°
  • Argument of Periapsis: 209.43°
  • Mean Anomaly: 61.58°

Physical Characteristics

  • Diameter: 5.70000 km
  • Magnitude: 13.52
  • Albedo: 0.163
  • Spectral type (Tholen): SG

Derived Characteristics

  • Orbit Period: 1,160 days (3.18 years)
  • Avg. Orbit Speed: 20.27 km/s
  • Aphelion Distance: 3.97 AU
  • Perihelion Distance: 0.35 AU
  • Rotation Period: 48.00 hours

Map Comparison

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Orbit Simulation

Sky Map

The position of Hephaistos 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.

Size Rendering

The above comparison is an artistic rendering that uses available data on the diameter of Hephaistos to create an approximate landscape rendering with Mount Everest in the background. This approximation is built for full-resolution desktop browsers. Shape, color, and texture of asteroid are imagined.