Key Facts

Overview

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

Dione orbits the sun every 2,070 days (5.67 years), coming as close as 2.68 AU and reaching as far as 3.69 AU from the sun. Dione is about 207.9 kilometers in diameter, making it larger than 99% of asteroids, comparable in size to the U.S. state of Maryland.

The rotation of Dione has been observed. It completes a rotation on its axis every 16.21 hours.

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

No Close Approaches

Dione's orbit is 1.68 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

Dione's orbit is determined by observations dating back to March 16, 1871. It was last officially observed on July 3, 2023. The IAU Minor Planet Center records 8,698 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 Dione:

References

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Orbital Elements

  • Epoch: 2460200.5 JD
  • Semi-major axis: 3.182 AU
  • Eccentricity: 0.1593
  • Inclination: 4.58°
  • Longitude of Ascending Node: 61.99°
  • Argument of Periapsis: 331.58°
  • Mean Anomaly: 141.27°

Physical Characteristics

  • Diameter: 207.86900 km
  • Magnitude: 7.84
  • Albedo: 0.044
  • Spectral type (Tholen): G
  • Spectral type (SMASS): Cgh

Derived Characteristics

  • Orbit Period: 2,070 days (5.67 years)
  • Avg. Orbit Speed: 16.72 km/s
  • Aphelion Distance: 3.69 AU
  • Perihelion Distance: 2.68 AU
  • Rotation Period: 16.21 hours
  • Approx. Composition: water, iron, nickel, cobalt, nitrogen, and ammonia.

Map Comparison

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Orbit Simulation

Sky Map

The position of Dione 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.