Key Facts


23P/Brorsen-Metcalf is a large comet with a medium-length orbit that is highly inclined to the ecliptic plane of the solar system. NASA JPL has classified 23P/Brorsen-Metcalf as a "Near Earth Asteroid" due to its orbit's proximity to Earth, but it is not considered potentially hazardous because computer simulations have not indicated any imminent likelihood of future collision.

23P/Brorsen-Metcalf orbits the sun every 25,800 days (70.64 years), coming as close as 0.48 AU and reaching as far as 33.66 AU from the sun. Its orbit is highly elliptical. Based on its brightness and the way it reflects light, 23P/Brorsen-Metcalf 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

23P/Brorsen-Metcalf's orbit is 0.19 AU from Earth's orbit at its closest point. This means that there is an 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

23P/Brorsen-Metcalf's orbit is determined by observations dating back to Aug. 1, 1847. It was last officially observed on Sept. 9, 1989. The IAU Minor Planet Center records 223 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 23P/Brorsen-Metcalf:



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Orbital Elements

  • Epoch: 2447800.5 JD
  • Semi-major axis: 17.07 AU
  • Eccentricity: 0.972
  • Inclination: 19.33°
  • Longitude of Ascending Node: 311.59°
  • Argument of Periapsis: 129.61°
  • Mean Anomaly: 0.27°

Physical Characteristics

  • Diameter: ~3431.463 km
  • Magnitude: 7.8

Derived Characteristics

  • Orbit Period: 25,800 days (70.64 years)
  • Avg. Orbit Speed: 7.20 km/s
  • Aphelion Distance: 33.66 AU
  • Perihelion Distance: 0.48 AU

Map Comparison

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Orbit Simulation

Sky Map

The position of 23P/Brorsen-Metcalf 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.