Key Facts


39P/Oterma is a large comet whose orbit is approximately between Jupiter and Neptune. NASA JPL has not classified 39P/Oterma as potentially hazardous because its orbit does not bring it close to Earth.

39P/Oterma orbits the sun every 7,080 days (19.38 years), coming as close as 5.46 AU and reaching as far as 8.97 AU from the sun. Based on its brightness and the way it reflects light, 39P/Oterma is probably between 2658.000 to 5943.469 kilometers in diameter, making it the largest asteroid/dwarf planet, very roughly comparable in size to the U.S. state of Alaska.

No Close Approaches

39P/Oterma's orbit is 4.46 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

39P/Oterma's orbit is determined by observations dating back to Feb. 17, 1942. It was last officially observed on July 5, 2019. The IAU Minor Planet Center records 245 observations used to determine its orbit.

Accessibility and Exploration

This comet 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 39P/Oterma:



   or view a random object

Orbital Elements

  • Epoch: 2442376.5 JD
  • Semi-major axis: 7.214 AU
  • Eccentricity: 0.2431
  • Inclination: 1.95°
  • Longitude of Ascending Node: 332.17°
  • Argument of Periapsis: 55.93°
  • Mean Anomaly: 200.99°

Physical Characteristics

  • Diameter: ~3431.463 km
  • Magnitude: 5.0

Derived Characteristics

  • Orbit Period: 7,080 days (19.38 years)
  • Avg. Orbit Speed: 11.08 km/s
  • Aphelion Distance: 8.97 AU
  • Perihelion Distance: 5.46 AU

Map Comparison

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Orbit Simulation

Sky Map

The position of 39P/Oterma 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.