21P/Giacobini-Zinner is a mid-sized 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 5.99 AU from the sun. Its orbit is highly elliptical. 21P/Giacobini-Zinner is about 2.0 kilometers in diameter, making it larger than 99% of asteroids, comparable in size to Mount Everest.
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.
21P/Giacobini-Zinner's orbit is determined by observations dating back to May 1, 2011. It was last officially observed on Jan. 30, 2020. The IAU Minor Planet Center records 1,983 observations used to determine its orbit.
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.