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Comets » 

Comet 17P/Holmes

Below the horizon.  Rise: 13:22 | Tran: 18:20 | Set: 23:18
Alt: -9.29°   Az: 262.78°   Direction: South-West

Comet 17P/Holmes is in the constellation of Crater, at a distance of 738,979,387.0 kilometers from Earth. The current Right Ascension is 11h 33m 03s and the Declination is -11° 44’ 33” (apparent coordinates). The estimated magnitude of comet 17P/Holmes, computed using JPL Horizons's data, is 23.12).

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 31m 46s
Dec: -11° 36’ 06”
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 33m 03s
-11° 44’ 33”
06h 00m 48s
17h 33m 52s

J2000

11h 31m 46s
-11° 36’ 06”

Additional Information

Crater
n/a
n/a
n/a
n/a
23.12

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: 101.7°
Max altitude: 26.8°
Azimuth: 258.3°

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 738,979,387.0 kilometers, equivalent to 4.9397720940 Astronomical Units. Light takes 41m 4.970s to travel from comet 17P/Holmes and arrive to us.

738,979,387.0
4.9397720940
41m 4.970s

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
Jun 17 2025 11h 30m 42s -11° 43’ 08” 23.09 Crater
Jun 18 2025 11h 30m 58s -11° 43’ 02” 23.09 Crater
Jun 19 2025 11h 31m 14s -11° 43’ 01” 23.10 Crater
Jun 20 2025 11h 31m 31s -11° 43’ 04” 23.10 Crater
Jun 21 2025 11h 31m 48s -11° 43’ 12” 23.11 Crater
Jun 22 2025 11h 32m 06s -11° 43’ 26” 23.11 Crater
Jun 23 2025 11h 32m 24s -11° 43’ 44” 23.11 Crater
Jun 24 2025 11h 32m 44s -11° 44’ 06” 23.12 Crater
Jun 25 2025 11h 33m 04s -11° 44’ 34” 23.12 Crater
Jun 26 2025 11h 33m 24s -11° 45’ 06” 23.13 Crater
Jun 27 2025 11h 33m 45s -11° 45’ 43” 23.13 Crater
Jun 28 2025 11h 34m 07s -11° 46’ 25” 23.13 Crater
Jun 29 2025 11h 34m 29s -11° 47’ 11” 23.14 Crater
Jun 30 2025 11h 34m 52s -11° 48’ 03” 23.14 Crater

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