Your guide to the Solar System and the night sky
By donating now you help keep this site alive and free from ads. Please consider supporting this project, thank you!
🌎  Observing from: Greenwich, United Kingdom [change]

Comet 21P/Giacobini-Zinner

Comet 21P/Giacobini-Zinner is currently in the constellation of Virgo. The current Right Ascension of Comet 21P/Giacobini-Zinner is 14h 09m 14s and the Declination is -08° 05’ 05” (topocentric coordinates computed for the selected location: Greenwich, United Kingdom [change]). The current estimated magnitude of Comet 21P/Giacobini-Zinner is 23.00 (JPL).

Summary of key facts about Comet 21P/Giacobini-Zinner [tip: you can also create a Quick Access page for this data if you access it frequently and would like to have a simpler view]:

14h 09m 14s
-08° 05’ 05”
  • 21P/Giacobini-Zinner is above the horizon from Greenwich, United Kingdom [change].
  • It is visible looking in the West-South-West direction at an altitude of 12° above the horizon.
  • Given its current magnitude, 21P/Giacobini-Zinner is visible only through long exposure photography.
  • See also 21P/Giacobini-Zinner rise and set times.
  • Go to interactive sky chart

If you need to access this information frequently for your observations, you can create a simple customized Quick Access page, so that you can easily bookmark it in your browser favorites or add a shortcut to your mobile phones' home screen.

Additional information about Comet 21P/Giacobini-Zinner available on TheSkyLive:

Available Resources

Comet 21P/Giacobini-Zinner Position and Finder Charts

Below we provide Comet 21P/Giacobini-Zinner finder charts showing where the object is right now in the sky with respect to the brightest stars. The first finder chart has a field of view of 50 degrees, while the second one has a field of view of 10 degrees. Click on each finder chart to access a full screen interactive Online Planetarium.

Map showing Comet 21P/Giacobini-Zinner in Virgo on January, 29 2023
Field of view: 50x30 degrees
View fullscreen
Map showing Comet 21P/Giacobini-Zinner in Virgo on January, 29 2023
Field of view: 10x6 degrees
View fullscreen
 = visible to the naked eye
 = binocular, brighter than 10th magnitude
= current altitude ≥ 30°   = current altitude < 30°   = below the horizon
Location: Greenwich, United Kingdom [change]

Higher precision deep sky finder chart, 60 arcmin wide, showing where Comet 21P/Giacobini-Zinner is right now. Click on the image to see a more detailed fullscreen tracker view.

RA: 14h 09m 14s
Dec: -08° 05’ 05”
Deep sky finder chart for Comet 21P/Giacobini-Zinner
Field of view: 60x40 arcmins
View fullscreen

Also check out Where is Comet 21P/Giacobini-Zinner?, a page that provides all the information needed to find Comet 21P/Giacobini-Zinner in the sky and additional links to sky charts.

Comet 21P/Giacobini-Zinner Distance from Earth

The distance of Comet 21P/Giacobini-Zinner from Earth is currently 791,406,333 kilometers, equivalent to 5.290225 Astronomical Units. Light takes 43 minutes and 59.8474 seconds to travel from Comet 21P/Giacobini-Zinner and arrive to us.

43 minutes and 59.8474 seconds

The following chart shows the distance of Comet 21P/Giacobini-Zinner from Earth as a function of time. In the chart the distance data is measured in Astronomical Units and sampled with an interval of 1 day.

Distance of Comet 21P/Giacobini-Zinner from Earth between January 2013 and December 2100

The value of the reported distance might be somewhat inaccurate around the times of closest approach for objects passing extremely close to Earth. The value of the distance of 21P/Giacobini-Zinner from Earth is also available as a real time updated value in the Live Position and Data Tracker.

Closest approach of Comet 21P/Giacobini-Zinner to Earth

Between January 2013 and December 2100, the closest approach of Comet 21P/Giacobini-Zinner to Earth happens on Fri Oct 28 2078 at a distance of 0.255783 Astronomical Units, or 38,264,665 kilometers:

Fri Oct 28 2078

NOTE: values for the closest approach are computed with a sampling interval of 1 day.

Comet 21P/Giacobini-Zinner brightness

The current visual magnitude of Comet 21P/Giacobini-Zinner is 23.00.


The observed magnitude and coma diameter values are derived from the Comet Observers Database by averaging the values reported in recent observations (more recent than 4 days), when available. The Estimated Magnitude comes from the JPL Horizons ephemerides service and might be inaccurate given the highly dynamic and unpredictable behavior of comets. When available, please refer to the Observed Magnitude value and consider the Estimated Magnitude as a directional indication. We acknowledge with thanks the comet observations from the COBS Comet Observation Database contributed by observers worldwide and used in this table to report recent comet observations.

The following chart is the predicted light curve (visual magnitude as a function of time) of Comet 21P/Giacobini-Zinner, according to the most recent ephemerides data. Magnitude data is sampled with a 2 days interval and there might be inaccuracies for objects changing brightness very rapidly during the course of a few days. For comets there could be large discrepancies between the observed and predicted brightness because of their highly dynamic behaviour.

Predicted magnitude of Comet 21P/Giacobini-Zinner between January 2013 and December 2100

Comet 21P/Giacobini-Zinner rise and set times

Location: Greenwich, United Kingdom [change]
Latitude: 51° 28’ 47” N
Longitude: 0° 00’ 00” E
Timezone: Europe/London

Today's Comet 21P/Giacobini-Zinner rise, transit and set times from Greenwich, United Kingdom [change] are the following (all times relative to the local timezone Europe/London):

Azimuth: 98.1°
Max altitude: 30.4°
Azimuth: 261.9°

The rise and set times are defined as the time at which the upper limb of Comet 21P/Giacobini-Zinner touches the horizon, considering the effect of the atmospheric refraction. As the atmospheric conditions cannot be modeled precisely the times reported here should be considered correct with an approximation of few minutes.

Comet 21P/Giacobini-Zinner Orbital Elements

The following table lists the orbital elements of Comet 21P/Giacobini-Zinner at epoch 05 November 2017 00:00 UTC (JD: 2458063.5). Source: JPL Small-Body Database

Element Symbol Value
Orbit eccentricity e 0.71046678
Orbit inclination i 32.00303376°
Perihelion distance q 1.01349375 AU
151,616,507 km
Aphelion distance Q 5.98738696 AU
895,700,342 km
Semi-major axis a 3.50044036 AU
523,658,425 km
Orbital period period 6.5493 years
2,392.1172 days
Date of perihelion transit Tp 2018-Sep-10 06:22:16
2,458,371.7655 JD
Next perihelion transit 2025-Mar-29 09:11
2,460,763.8826 JD
Argument of perihelion peri 172.80915964581°
Longitude of the ascending node node 195.40514495049°
Mean anomaly M 313.60780403717°
Mean motion n 0.15049430°/day

Visualization of Comet 21P/Giacobini-Zinner Orbit

This 3d orbit diagram is a feature of our 3D Solar System Simulator and shows the orbit of Comet 21P/Giacobini-Zinner with respect of the Sun and the orbits of the major planets. The position of Comet 21P/Giacobini-Zinner and the planets along their orbits in this diagram accurately represents the current configuration of the objects in the Solar System. This is an experimental feature and it requires a WebGL enabled browser. Please provide us feedback!

Orbit Diagram of Comet 21P/Giacobini-Zinner
View Comet 21P/Giacobini-Zinner in the 3D Solar System Simulator

Comet 21P/Giacobini-Zinner 15 Days Ephemeris

The following table lists the ephemerides of Comet 21P/Giacobini-Zinner computed for the past and next 7 days, with a 24 hours interval. Click on each row of the table to locate Comet 21P/Giacobini-Zinner in our Online Planetarium at the chosen date.

Date Right AscensionR.A. DeclinationDec. MagnitudeMag Constellation
2023 Jan 22 14h 07m 53s -08° 15’ 24” 23.07 Virgo
2023 Jan 23 14h 08m 05s -08° 14’ 15” 23.06 Virgo
2023 Jan 24 14h 08m 17s -08° 13’ 00” 23.05 Virgo
2023 Jan 25 14h 08m 30s -08° 11’ 43” 23.04 Virgo
2023 Jan 26 14h 08m 41s -08° 10’ 19” 23.03 Virgo
2023 Jan 27 14h 08m 52s -08° 08’ 53” 23.02 Virgo
2023 Jan 28 14h 09m 02s -08° 07’ 21” 23.01 Virgo
2023 Jan 29 14h 09m 11s -08° 05’ 44” 23.00 Virgo
2023 Jan 30 14h 09m 20s -08° 04’ 03” 22.99 Virgo
2023 Jan 31 14h 09m 28s -08° 02’ 17” 22.98 Virgo
2023 Feb 01 14h 09m 34s -08° 00’ 27” 22.97 Virgo
2023 Feb 02 14h 09m 42s -07° 58’ 32” 22.96 Virgo
2023 Feb 03 14h 09m 47s -07° 56’ 31” 22.95 Virgo
2023 Feb 04 14h 09m 51s -07° 54’ 28” 22.94 Virgo