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Comet 17P/Holmes

Below the horizon.  Rise: 12:14 | Tran: 17:10 | Set: 22:06
Alt: -7.07°   Az: 259.32°   Direction: West

Comet 17P/Holmes is in the constellation of Crater, at a distance of 778,530,993.0 kilometers from Earth. The current Right Ascension is 11h 41m 40s and the Declination is -12° 09’ 52” (apparent coordinates). The estimated magnitude of comet 17P/Holmes, computed using JPL Horizons's data, is 23.20.

Finder Charts

The sky charts below show, at different resolutions, the position of comet 17P/Holmes in the sky. Click on each chart to access the interactive star map tool.

Star map showing the position of comet 17P/Holmes in the constellation of Crater on F, d Y. Field of view: 50x30 degrees. View interactive star map.
Star map showing the position of comet 17P/Holmes in the constellation of Crater on F, d Y. Field of view: 15x9 degrees. View in interactive star map.

The following map uses photographic imagery from the Digitized Sky Survey (DSS) to realistically visualize the precise position of comet 17P/Holmes 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.

17P/Holmes
RA: 11h 40m 22s
Dec: -12° 01’ 22”
Simplified high-resolution deep sky chart showing the current position of comet 17P/Holmes. Field of view: 60 x 40 arcminutes. Go to the dedicated page

Equatorial Coordinates

Apparent

11h 41m 40s
-12° 09’ 52”
05h 44m 13s
17h 25m 53s

J2000

11h 40m 22s
-12° 01’ 22”

Additional Information

Crater
n/a
n/a
n/a
n/a
23.20

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 17P/Holmes from Greenwich, UK (all times relative to the local timezone Europe/London):

Azimuth: 102.1°
Max altitude: 26.4°
Azimuth: 257.8°

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 17P/Holmes from Earth is currently 778,530,993.0 kilometers, equivalent to 5.2041582501 Astronomical Units. Light takes 43m 16.900s to travel from comet 17P/Holmes and arrive to us.

778,530,993.0
5.2041582501
43m 16.900s

The following graph shows the distance of comet 17P/Holmes 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.

Chart of the distance of comet 17P/Holmes from Earth in Astronomical Units (au)
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 17P/Holmes 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 17P/Holmes to Earth will happen on Thursday 20 August 2048 at a distance of 1.146026 Astronomical Units, or 171,443,013 kilometers:

Thursday 20 August 2048
171,443,013
1.146026

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 17P/Holmes, 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.

Chart of the magnitude of comet 17P/Holmes as a function of time

Orbital Elements

The following table lists the orbital elements of comet 17P/Holmes at epoch October, 18 2016 00:00 UTC (JD: 2457680.5). Source: JPL Small-Body Database

Element Symbol Value
Orbit eccentricity e 0.43015482
Orbit inclination i 19.07035853°
Perihelion distance q 2.06632925 AU
309,118,457 km
Aphelion distance Q 5.18591870 AU
775,802,397 km
Semi-major axis a 3.62612398 AU
542,460,427 km
Orbital period period 6.9051 years
2,522.1006 days
Date of perihelion transit Tp March 26, 2014
2,456,743.2203 JD
Next perihelion transit February 19, 2021
2,459,265.3209 JD
Argument of perihelion peri 24.738506005017°
Longitude of the ascending node node 326.77381045426°
Mean anomaly M 133.78558143669°
Mean motion n 0.14273816°/day

Orbit Visualization

The following chart is a 3D animated visualization of the orbit of comet 17P/Holmes 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 17P/Holmes 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 07 2025 11h 37m 49s -11° 56’ 14” 23.17 Crater
Jul 08 2025 11h 38m 16s -11° 57’ 42” 23.17 Crater
Jul 09 2025 11h 38m 44s -11° 59’ 14” 23.18 Crater
Jul 10 2025 11h 39m 12s -12° 00’ 51” 23.18 Crater
Jul 11 2025 11h 39m 41s -12° 02’ 33” 23.18 Crater
Jul 12 2025 11h 40m 11s -12° 04’ 20” 23.19 Crater
Jul 13 2025 11h 40m 41s -12° 06’ 10” 23.19 Crater
Jul 14 2025 11h 41m 11s -12° 08’ 04” 23.19 Crater
Jul 15 2025 11h 41m 42s -12° 10’ 03” 23.20 Crater
Jul 16 2025 11h 42m 13s -12° 12’ 06” 23.20 Crater
Jul 17 2025 11h 42m 45s -12° 14’ 14” 23.20 Crater
Jul 18 2025 11h 43m 17s -12° 16’ 25” 23.20 Crater
Jul 19 2025 11h 43m 50s -12° 18’ 41” 23.21 Crater
Jul 20 2025 11h 44m 23s -12° 21’ 01” 23.21 Crater

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