Key Facts

Overview

21P/Giacobini-Zinner is a small comet whose orbit features a relatively short period, low inclination, and is controlled by Jupiter's gravitational effects. NASA JPL has classified 21P/Giacobini-Zinner 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.

21P/Giacobini-Zinner orbits the sun every 2,390 days (6.54 years), coming as close as 1.01 AU and reaching as far as 5.98 AU from the sun. Its orbit is highly elliptical. 21P/Giacobini-Zinner is about 2.0 kilometers in diameter, making it larger than most asteroids, comparable in size to Mount Everest.

No Close Approaches

21P/Giacobini-Zinner's orbit is 0.02 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

21P/Giacobini-Zinner's orbit is determined by observations dating back to Nov. 19, 2012. It was last officially observed on April 11, 2019. The IAU Minor Planet Center records 3,833 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 21P/Giacobini-Zinner:

References

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Orbital Elements

  • Epoch: 2458339.5 JD
  • Semi-major axis: 3.49809338274 AU
  • Eccentricity: 0.710463550896
  • Inclination: 31.9978262573°
  • Longitude of Ascending Node: 195.391987464°
  • Argument of Periapsis: 172.860553258°
  • Mean Anomaly: 355.137523923°

Physical Characteristics

  • Diameter: 2.00000 km
  • Magnitude: 13.1

Derived Characteristics

  • Orbit Period: 2,390 days (6.54 years)
  • Avg. Orbit Speed: 15.92 km/s
  • Aphelion Distance: 5.98 AU
  • Perihelion Distance: 1.01 AU

Size Comparison

Orbit Simulation

Sky Map

The position of 21P/Giacobini-Zinner 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.