Key Facts


Comet C/2021 S4 (Tsuchinshan) is an object whose orbit is approximately between Jupiter and Neptune. NASA JPL has not classified Tsuchinshan as potentially hazardous because its orbit does not bring it close to Earth.

Tsuchinshan orbits the sun every 768,000 days (2,102.67 years), coming as close as 6.70 AU and reaching as far as 321.50 AU from the sun. Its orbit is highly elliptical.

No Close Approaches

Tsuchinshan's orbit is 5.75 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

Tsuchinshan's orbit is determined by observations dating back to Sept. 8, 2021. It was last officially observed on Aug. 3, 2023. The IAU Minor Planet Center records 392 observations used to determine its orbit.

Accessibility and Exploration

This comet is not considered a viable target for human exploration by the NHATS study.



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Orbital Elements

  • Epoch: 2459818.5 JD
  • Semi-major axis: 164.1 AU
  • Eccentricity: 0.9592
  • Inclination: 17.48°
  • Longitude of Ascending Node: 5.5°
  • Argument of Periapsis: 72.76°
  • Mean Anomaly: 359.77°

Physical Characteristics

  • Magnitude: 6.5

Derived Characteristics

  • Orbit Period: 768,000 days (2,102.67 years)
  • Avg. Orbit Speed: 2.32 km/s
  • Aphelion Distance: 321.50 AU
  • Perihelion Distance: 6.70 AU

Orbit Simulation

Sky Map

The position of C/2021 S4 (Tsuchinshan) 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.