Comet 21P/Giacobini-Zinner
Comet 21P/Giacobini-Zinner is in the constellation of
Pisces,
at a distance of
Finder Charts
View interactive star map
High 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.
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.
Celestial Coordinates
Apparent
J2000
Additional Information
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.
Rise and Set Times
Today's rise, transit and set times of Comet 21P/Giacobini-Zinner from Greenwich, UK (all times relative to the local timezone Europe/London):
- 21P/Giacobini-Zinner is below the horizon from Greenwich, UK.
- Given its current magnitude, 21P/Giacobini-Zinner is visible with the help of a telescope having an aperture of 20 inches (500mm) or more.
- 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.
Distance from Earth
The distance of Comet 21P/Giacobini-Zinner from Earth is currently
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.
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
Between 1 January 2000 and 31 December 2099, the closest approach of Comet 21P/Giacobini-Zinner to Earth happens on Sun Oct 30 2078 at a distance of 0.289030 Astronomical Units, or 43,238,333 kilometers:
NOTE: values for the closest approach are computed with a sampling interval of 1 day.
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.
Orbital Elements
The following table lists the orbital elements of Comet 21P/Giacobini-Zinner at epoch 12 November 2017 00:00 UTC (JD: 2458070.5). Source: JPL Small-Body Database
| Element | Symbol | Value |
|---|---|---|
| Orbit eccentricity | e | 0.71047048 |
| Orbit inclination | i | 32.00259232° |
| Perihelion distance | q | 1.01344100 AU 151,608,616 km |
| Aphelion distance | Q |
5.98716470 AU 895,667,092 km |
| Semi-major axis | a |
3.50030285 AU 523,637,854 km |
| Orbital period | period |
6.5489 years 2,391.9762 days |
| Date of perihelion transit | Tp | 2018-Sep-10 06:22:53 2,458,371.7659 JD |
| Next perihelion transit | 2025-Mar-29 05:48 2,460,763.7421 JD |
|
| Argument of perihelion | peri | 172.81248242749° |
| Longitude of the ascending node | node | 195.40448019669° |
| Mean anomaly | M | 314.65852733856° |
| Mean motion | n | 0.15050317°/day |
Orbit Visualization
View Comet 21P/Giacobini-Zinner in the 3D Solar System Simulator
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. Apparent celestial coordinates are provided.
| Date | Right AscensionR.A. | DeclinationDec. | MagnitudeMag | Constellation |
|---|---|---|---|---|
| 2025 Apr 05 | 01h 10m 05s | +05° 35’ 52” | 14.80 | Pisces |
| 2025 Apr 06 | 01h 14m 23s | +05° 40’ 34” | 14.81 | Pisces |
| 2025 Apr 07 | 01h 18m 41s | +05° 45’ 07” | 14.82 | Pisces |
| 2025 Apr 08 | 01h 22m 58s | +05° 49’ 33” | 14.83 | Pisces |
| 2025 Apr 09 | 01h 27m 15s | +05° 53’ 51” | 14.84 | Pisces |
| 2025 Apr 10 | 01h 31m 31s | +05° 58’ 00” | 14.86 | Pisces |
| 2025 Apr 11 | 01h 35m 48s | +06° 02’ 03” | 14.87 | Pisces |
| 2025 Apr 12 | 01h 40m 03s | +06° 05’ 56” | 14.89 | Pisces |
| 2025 Apr 13 | 01h 44m 17s | +06° 09’ 41” | 14.90 | Pisces |
| 2025 Apr 14 | 01h 48m 31s | +06° 13’ 17” | 14.92 | Pisces |
| 2025 Apr 15 | 01h 52m 44s | +06° 16’ 45” | 14.93 | Pisces |
| 2025 Apr 16 | 01h 56m 56s | +06° 20’ 05” | 14.95 | Pisces |
| 2025 Apr 17 | 02h 01m 08s | +06° 23’ 16” | 14.97 | Pisces |
| 2025 Apr 18 | 02h 05m 18s | +06° 26’ 19” | 14.99 | Pisces |
Additional Resources
- Position and finder charts (see also Where is Comet 21P/Giacobini-Zinner?)
- Distance from Earth (see also How far is Comet 21P/Giacobini-Zinner from Earth?)
- When does Comet 21P/Giacobini-Zinner rise and set?
- Brightness (see also How bright is Comet 21P/Giacobini-Zinner?)
- Orbital elements. Detailed information about Comet 21P/Giacobini-Zinner orbital parameters.
- Interactive orbit visualization. 3d visualization showing the orbit of Comet 21P/Giacobini-Zinner with respect to the major Solar System objects.
- 15 days ephemerides. Table showing celestial coordinates and magnitude of Comet 21P/Giacobini-Zinner for the past and next 7 days.
- Interactive sky chart. An online planetarium application that shows where to locate Comet 21P/Giacobini-Zinner in the sky from your location.
- Live position tracker. A high precision sky chart that uses real deep sky imagery to help locate Comet 21P/Giacobini-Zinner with your telescope or on your astrophotographies.