Key Facts


Armstrong is a mid-sized asteroid orbiting between Mars and Jupiter in the main portion of the asteroid belt. NASA JPL has not classified Armstrong as potentially hazardous because its orbit does not bring it close to Earth.

Armstrong orbits the sun every 1,210 days (3.31 years), coming as close as 1.77 AU and reaching as far as 2.67 AU from the sun. Armstrong is about 3.7 kilometers in diameter, making it larger than 99% of asteroids, comparable in size to the island of Manhattan.

The rotation of Armstrong has been observed. It completes a rotation on its axis every 5.97 days.

No Close Approaches

Armstrong's orbit is 0.76 AU from Earth's orbit at its closest point. This means that there is an very wide berth between this asteroid and Earth at all times.

Orbital simulations conducted by NASA JPL's CNEOS do not show any close approaches to Earth.

Images and Observations

Armstrong's orbit is determined by observations dating back to Oct. 16, 1969. It was last officially observed on Feb. 1, 2020. The IAU Minor Planet Center records 1,592 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 Armstrong:



   or view a random object

Orbital Elements

  • Epoch: 2459000.5 JD
  • Semi-major axis: 2.22 AU
  • Eccentricity: 0.2037
  • Inclination: 3.96°
  • Longitude of Ascending Node: 159.38°
  • Argument of Periapsis: 150.66°
  • Mean Anomaly: 164.4°

Physical Characteristics

  • Diameter: 3.72000 km
  • Magnitude: 14.5
  • Albedo: 0.243

Derived Characteristics

  • Orbit Period: 1,210 days (3.31 years)
  • Avg. Orbit Speed: 19.96 km/s
  • Aphelion Distance: 2.67 AU
  • Perihelion Distance: 1.77 AU
  • Rotation Period: 5.97 hours

Map Comparison

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Orbit Simulation

Sky Map

The position of Armstrong 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.