Key Facts

  • Categorized as a Main-belt Asteroid
  • Comparable in size to the U.S. state of Connecticut (147.97 km diameter)
  • Not a Near Earth Object
  • Not a Potentially Hazardous Object
  • See orbit simulation

Overview

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

Arethusa orbits the sun every 1,960 days (5.37 years), coming as close as 2.59 AU and reaching as far as 3.53 AU from the sun. Arethusa is about 148.0 kilometers in diameter, making it larger than 99% of asteroids, comparable in size to the U.S. state of Connecticut.

The rotation of Arethusa has been observed. It completes a rotation on its axis every 8.71 hours.

Arethusa's spectral type C (Tholen) / Ch (SMASSII) indicates that it is likely to contain water, iron, nickel, cobalt, nitrogen, and ammonia.

No Close Approaches

Arethusa's orbit is 1.61 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

Arethusa's orbit is determined by observations dating back to Sept. 23, 1872. It was last officially observed on Aug. 9, 2021. The IAU Minor Planet Center records 3,292 observations used to determine its orbit.

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

View asteroid Arethusa 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 Arethusa:

References

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Orbital Elements

  • Epoch: 2459396.5 JD
  • Semi-major axis: 3.063 AU
  • Eccentricity: 0.1531
  • Inclination: 13.0°
  • Longitude of Ascending Node: 243.02°
  • Argument of Periapsis: 153.71°
  • Mean Anomaly: 220.61°

Physical Characteristics

  • Diameter: 147.96900 km
  • Magnitude: 8.05
  • Albedo: 0.058
  • Spectral type (Tholen): C
  • Spectral type (SMASS): Ch

Derived Characteristics

  • Orbit Period: 1,960 days (5.37 years)
  • Avg. Orbit Speed: 17.00 km/s
  • Aphelion Distance: 3.53 AU
  • Perihelion Distance: 2.59 AU
  • Rotation Period: 8.71 hours
  • Approx. Composition: water, iron, nickel, cobalt, nitrogen, and ammonia.

Map Comparison

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Orbit Simulation

Sky Map

The position of Arethusa 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.