Key Facts


Aethra is a large asteroid with an orbit that crosses the orbit of Mars. NASA JPL has not classified Aethra as potentially hazardous because its orbit does not bring it close to Earth.

Aethra orbits the sun every 1,540 days (4.22 years), coming as close as 1.60 AU and reaching as far as 3.62 AU from the sun. Aethra is about 42.9 kilometers in diameter, making it larger than 99% of asteroids, comparable in size to the U.S. state of Rhode Island.

The rotation of Aethra has been observed. It completes a rotation on its axis every 5.17 hours.

Aethra's spectral type M (Tholen) / Xe (SMASSII) indicates that it is likely to contain iron, nickel, and cobalt.

No Close Approaches

Aethra's orbit is 0.78 AU from Earth's orbit at its closest point. This means that there is a 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

Aethra's orbit is determined by observations dating back to June 14, 1873. It was last officially observed on July 4, 2023. The IAU Minor Planet Center records 3,699 observations used to determine its orbit.

Scientists have been able to determine this object's shape:

View asteroid Aethra in 3D.

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 Aethra:



   or view a random object

Orbital Elements

  • Epoch: 2460200.5 JD
  • Semi-major axis: 2.613 AU
  • Eccentricity: 0.3871
  • Inclination: 24.97°
  • Longitude of Ascending Node: 258.07°
  • Argument of Periapsis: 255.53°
  • Mean Anomaly: 286.39°

Physical Characteristics

  • Diameter: 42.87000 km
  • Magnitude: 8.94
  • Albedo: 0.1990
  • Spectral type (Tholen): M
  • Spectral type (SMASS): Xe

Derived Characteristics

  • Orbit Period: 1,540 days (4.22 years)
  • Avg. Orbit Speed: 18.46 km/s
  • Aphelion Distance: 3.62 AU
  • Perihelion Distance: 1.60 AU
  • Rotation Period: 5.17 hours
  • Approx. Composition: iron, nickel, and cobalt.

Map Comparison

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Orbit Simulation

Sky Map

The position of Aethra 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.