Find it in the Sky
Chose a date & time and view the position of comet 21P/Giacobini-Zinner in the sky on our interactive planetarium.
In Evidence
Comet 21P/Giacobini-Zinner
Comet 21P/Giacobini-Zinner is in the constellation of Monoceros, at a distance of
Finder Charts
The sky charts below show, at different resolutions, the position of comet 21P/Giacobini-Zinner in the sky. Click on each chart to access the interactive star map tool.
The following map uses photographic imagery from the Digitized Sky Survey (DSS) to realistically visualize the precise position of comet 21P/Giacobini-Zinner against the stars in the background. The horizontal size of the map measures 60 arcminutes. Click on the image to access a more detailed full-screen view.
Equatorial 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
The following table lists today's rise, transit and set times of comet 21P/Giacobini-Zinner from Greenwich, UK (all times relative to the local timezone Europe/London):
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 graph shows the distance of comet 21P/Giacobini-Zinner from Earth as a function of time. In the chart the distance is measured in Astronomical Units and the data is sampled with an interval of 1 day.
Note: The values in this chart may not be entirely accurate around the time of closest approach for objects passing very close to Earth at high speed (e.g., Near-Earth Objects).
The value of the distance of 21P/Giacobini-Zinner from Earth is also available as a real time updated value in the live position tracker.
Closest Approach to Earth
In the period between January 1, 2000 and December 31, 2099, the closest approach of comet 21P/Giacobini-Zinner to Earth will happen on Sunday 30 October 2078 at a distance of 0.289030 Astronomical Units, or 43,238,333 kilometers:
Note: the values for the closest approach are computed with a sampling interval of 1 day.
Light Curve
The following chart shows the light curve of comet 21P/Giacobini-Zinner, i.e., its apparent magnitude as a function of time. The curve is calculated using the latest ephemerides provided by JPL Horizons. The magnitude data is sampled with the interval of 2 days. Because of this sampling, inaccuracies may occur for objects that have large variations of brightness over a few days. For comets, large discrepancies can arise between the calculated brightness and the observations due to their highly dynamic, and not always precisely predictable, behavior.
Orbital Elements
The following table lists the orbital elements of comet 21P/Giacobini-Zinner at epoch November, 12 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 | September 10, 2018 2,458,371.7659 JD |
| Next perihelion transit | March 29, 2025 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
The following chart is a 3D animated visualization of the orbit of comet 21P/Giacobini-Zinner relative to the other major objects in the Solar System. You can access more advanced features using our 3D Solar System Viewer.
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 |
|---|---|---|---|---|
| Jul 10 2025 | 06h 44m 32s | +02° 46’ 26” | 17.27 | Monoceros |
| Jul 11 2025 | 06h 47m 02s | +02° 39’ 13” | 17.30 | Monoceros |
| Jul 12 2025 | 06h 49m 31s | +02° 31’ 56” | 17.33 | Monoceros |
| Jul 13 2025 | 06h 51m 59s | +02° 24’ 34” | 17.35 | Monoceros |
| Jul 14 2025 | 06h 54m 26s | +02° 17’ 08” | 17.38 | Monoceros |
| Jul 15 2025 | 06h 56m 51s | +02° 09’ 38” | 17.40 | Monoceros |
| Jul 16 2025 | 06h 59m 16s | +02° 02’ 03” | 17.43 | Monoceros |
| Jul 17 2025 | 07h 01m 39s | +01° 54’ 25” | 17.45 | Monoceros |
| Jul 18 2025 | 07h 04m 02s | +01° 46’ 42” | 17.48 | Monoceros |
| Jul 19 2025 | 07h 06m 23s | +01° 38’ 56” | 17.50 | Monoceros |
| Jul 20 2025 | 07h 08m 44s | +01° 31’ 06” | 17.53 | Monoceros |
| Jul 21 2025 | 07h 11m 03s | +01° 23’ 11” | 17.55 | Canis Minoris |
| Jul 22 2025 | 07h 13m 22s | +01° 15’ 13” | 17.57 | Canis Minoris |
| Jul 23 2025 | 07h 15m 39s | +01° 07’ 11” | 17.60 | Monoceros |
Additional Resources on TheSkyLive
- Comet 21P/Giacobini-Zinner: Complete reference information on TheSkyLive.com.
- Where is comet 21P/Giacobini-Zinner?: Key information on where to find comet 21P/Giacobini-Zinner in the sky.
- Distance of comet 21P/Giacobini-Zinner from Earth: Find out how far comet 21P/Giacobini-Zinner is from Earth right now.
- How Bright is comet 21P/Giacobini-Zinner?: Current visual brightness (magnitude) and apparent size.
- Rise and Set Times: Rise and set times of comet 21P/Giacobini-Zinner from your location.
- Interactive Sky Map: Planetarium-style interactive visualization of comet 21P/Giacobini-Zinner's position in the sky.
- Live Position Tracker: High precision real time tracker of comet 21P/Giacobini-Zinner's position using deep space imagery.
- Ephemeris: 15 days comet 21P/Giacobini-Zinner's computed ephemeris.
- Orbital elements: Information about comet 21P/Giacobini-Zinner orbital parameters.
- Orbit Visualization: 3D interactive visualization showing the orbit of comet 21P/Giacobini-Zinner with respect to the major Solar System objects.