Key Facts

  • Categorized as a Main-belt Asteroid
  • Comparable in size to the U.S. state of Rhode Island (46.27 km diameter)
  • Not a Near Earth Object
  • Not a Potentially Hazardous Object
  • See orbit simulation


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

Erna orbits the sun every 1,820 days (4.98 years), coming as close as 2.40 AU and reaching as far as 3.44 AU from the sun. Erna is about 46.3 kilometers in diameter, making it larger than 99% of asteroids, comparable in size to the U.S. state of Rhode Island.

The rotation of Erna has been observed. It completes a rotation on its axis every 8.79 hours.

Erna's spectral type P (Tholen) / None (SMASSII) indicates that it is likely to contain .

No Close Approaches

Erna's orbit is 1.39 AU from Earth's orbit at its closest point. This means that there is an extremely 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

Erna's orbit is determined by observations dating back to Feb. 20, 1903. It was last officially observed on June 23, 2022. The IAU Minor Planet Center records 4,266 observations used to determine its orbit.

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

View asteroid Erna 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 Erna:



   or view a random object

Orbital Elements

  • Epoch: 2459800.5 JD
  • Semi-major axis: 2.918 AU
  • Eccentricity: 0.1783
  • Inclination: 4.19°
  • Longitude of Ascending Node: 315.48°
  • Argument of Periapsis: 37.71°
  • Mean Anomaly: 164.55°

Physical Characteristics

  • Diameter: 46.26600 km
  • Magnitude: 10.41
  • Albedo: 0.060
  • Spectral type (Tholen): P

Derived Characteristics

  • Orbit Period: 1,820 days (4.98 years)
  • Avg. Orbit Speed: 17.44 km/s
  • Aphelion Distance: 3.44 AU
  • Perihelion Distance: 2.40 AU
  • Rotation Period: 8.79 hours
  • Approx. Composition: .

Map Comparison

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Orbit Simulation

Sky Map

The position of Erna 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.