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A Complete Guide to the Solar System and the Night Sky
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public Observing fromLocation: Greenwich, United Kingdom edit_location_alt
north SunriseRise: 7:54  
clear_day Transit: 11:51  
SunsetSet: 15:49 south
sunny DaytimeWhat's Visible Now?
Comets » 

Comet 21P/Giacobini-Zinner

Altitude: 20.2°   Azimuth: 231.1°   Direction: South-West

Comet 21P/Giacobini-Zinner is currently in the constellation of Libra.

The current Right Ascension of Comet 21P/Giacobini-Zinner is 15h 02m 23s and the Declination is -05° 35’ 53” (topocentric coordinates computed for the selected location: Greenwich, United Kingdom edit_location_alt). The current estimated magnitude of Comet 21P/Giacobini-Zinner is 22.02 (JPL).

15h 02m 23s
-05° 35’ 53”

The observed values of Magnitude, Coma Diameter and Tail Length are derived from the most recent observation recorded at the Comet Observers Database. The value of Predicted Magnitude comes from the JPL Horizons ephemerides service and, in the case of comets, might be inaccurate given the highly dynamic and unpredictable behavior of these objects. When available, please refer to the Observed Magnitude value and consider the Predicted 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.

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

Azimuth: 95.6°
Max altitude: 32.9°
Azimuth: 264.4°
  • 21P/Giacobini-Zinner is above the horizon from Greenwich, United Kingdom edit_location_alt.
  • Right now it is placed in the South-West direction at an altitude of 20° above the horizon.
  • Given its current magnitude, 21P/Giacobini-Zinner is visible only through long exposure photography.
  • 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.

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.

Finder chart of 21P/Giacobini-Zinner in Libra on December,11 2023
Map showing Comet 21P/Giacobini-Zinner in Libra on December, 11 2023
Field of view: 50x30 degrees
View fullscreen
Finder chart of 21P/Giacobini-Zinner
Map showing Comet 21P/Giacobini-Zinner in Libra on December, 11 2023
Field of view: 10x6 degrees
View fullscreen

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: 15h 02m 23s
Dec: -05° 35’ 53”
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 759,739,958 kilometers, equivalent to 5.078548 Astronomical Units. Light takes 42 minutes and 14.2197 seconds to travel from Comet 21P/Giacobini-Zinner and arrive to us.

42 minutes and 14.2197 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.

Chart of the distance of Comet 21P/Giacobini-Zinner from Earth in Astronomical Units (au)

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 1 January 2013 and 30 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 and Light Curve

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.

Chart of the magnitude of Comet 21P/Giacobini-Zinner as a function of time

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 Dec 04 14h 55m 31s -05° 26’ 12” 22.10 Libra
2023 Dec 05 14h 56m 26s -05° 27’ 41” 22.09 Libra
2023 Dec 06 14h 57m 20s -05° 29’ 06” 22.08 Libra
2023 Dec 07 14h 58m 15s -05° 30’ 28” 22.07 Libra
2023 Dec 08 14h 59m 11s -05° 31’ 45” 22.06 Libra
2023 Dec 09 15h 00m 05s -05° 32’ 59” 22.05 Libra
2023 Dec 10 15h 01m 00s -05° 34’ 10” 22.04 Libra
2023 Dec 11 15h 01m 54s -05° 35’ 17” 22.03 Libra
2023 Dec 12 15h 02m 48s -05° 36’ 20” 22.02 Libra
2023 Dec 13 15h 03m 42s -05° 37’ 19” 22.01 Libra
2023 Dec 14 15h 04m 37s -05° 38’ 16” 22.00 Libra
2023 Dec 15 15h 05m 31s -05° 39’ 07” 21.99 Libra
2023 Dec 16 15h 06m 25s -05° 39’ 55” 21.98 Libra
2023 Dec 17 15h 07m 19s -05° 40’ 39” 21.97 Libra