Key Facts

  • Categorized as a Apollo-class Asteroid
  • Comparable in size to the island of Manhattan (3.18 km diameter)
  • Will pass within 29,300,951 km of Earth in 2118
  • Classified as a Near Earth Asteroid (NEA)
  • Not a Potentially Hazardous Object
  • See orbit simulation


Poseidon is a mid-sized asteroid whose orbit crosses the orbit of Earth. NASA JPL has classified Poseidon 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.

Poseidon orbits the sun every 908 days (2.49 years), coming as close as 0.59 AU and reaching as far as 3.08 AU from the sun. Poseidon is about 3.2 kilometers in diameter, making it larger than 99% of asteroids, comparable in size to the island of Manhattan.

The rotation of Poseidon has been observed. It completes a rotation on its axis every 6.26 hours.

Poseidon's spectral type None (Tholen) / O (SMASSII) indicates that it is likely to contain and .

Close Approaches

Poseidon's orbit is 0.19 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.

Poseidon has 2 close approaches predicted in the coming decades:

Date Distance from Earth (km) Velocity (km/s)
Nov. 5, 2118 29,300,951 18.730
April 30, 2166 29,200,083 20.993

Images and Observations

Poseidon's orbit is determined by observations dating back to May 29, 1987. It was last officially observed on Sept. 7, 2021. The IAU Minor Planet Center records 619 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 Poseidon:



   or view a random object

Orbital Elements

  • Epoch: 2459396.5 JD
  • Semi-major axis: 1.835 AU
  • Eccentricity: 0.68
  • Inclination: 11.84°
  • Longitude of Ascending Node: 108.06°
  • Argument of Periapsis: 15.82°
  • Mean Anomaly: 286.21°

Physical Characteristics

  • Diameter: 3.17700 km
  • Magnitude: 15.92
  • Albedo: 0.054
  • Spectral type (SMASS): O

Derived Characteristics

  • Orbit Period: 908 days (2.49 years)
  • Avg. Orbit Speed: 21.99 km/s
  • Aphelion Distance: 3.08 AU
  • Perihelion Distance: 0.59 AU
  • Rotation Period: 6.26 hours
  • Approx. Composition: and .

Map Comparison

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Orbit Simulation

Sky Map

The position of Poseidon 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 Poseidon 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.