Key Facts

  • Categorized as a Jupiter Trojan
  • Comparable in size to the U.S. state of Rhode Island (70.23 km diameter)
  • Not a Near Earth Object
  • Not a Potentially Hazardous Object
  • See orbit simulation


Protesilaos is a large asteroid that shares Jupiter's orbit around the sun. NASA JPL has not classified Protesilaos as potentially hazardous because its orbit does not bring it close to Earth.

Protesilaos orbits the sun every 4,430 days (12.13 years), coming as close as 4.67 AU and reaching as far as 5.90 AU from the sun. Protesilaos is about 70.2 kilometers in diameter, making it larger than 99% of asteroids, comparable in size to the U.S. state of Rhode Island.

The rotation of Protesilaos has been observed. It completes a rotation on its axis every 8.95 hours.

No Close Approaches

Protesilaos's orbit is 3.75 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

Protesilaos's orbit is determined by observations dating back to Feb. 14, 1953. It was last officially observed on Aug. 9, 2021. The IAU Minor Planet Center records 2,932 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 Protesilaos:



   or view a random object

Orbital Elements

  • Epoch: 2459396.5 JD
  • Semi-major axis: 5.281 AU
  • Eccentricity: 0.1165
  • Inclination: 23.28°
  • Longitude of Ascending Node: 26.43°
  • Argument of Periapsis: 115.97°
  • Mean Anomaly: 252.47°

Physical Characteristics

  • Diameter: 70.22500 km
  • Magnitude: 9.47
  • Albedo: 0.062

Derived Characteristics

  • Orbit Period: 4,430 days (12.13 years)
  • Avg. Orbit Speed: 12.97 km/s
  • Aphelion Distance: 5.90 AU
  • Perihelion Distance: 4.67 AU
  • Rotation Period: 8.95 hours

Map Comparison

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Orbit Simulation

Sky Map

The position of Protesilaos 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.