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🌎  Greenwich, United Kingdom [change]

Comet 17P/Holmes

Comet 17P/Holmes is currently in the constellation of Auriga. The current Right Ascension of Comet 17P/Holmes is 05h 59m 44s and the Declination is +46° 56’ 20” (topocentric coordinates computed for the selected location: Greenwich, United Kingdom [change]). The current estimated magnitude of Comet 17P/Holmes is 17.42 (JPL) while the latest observed magnitude is 17.0 (COBS).

Summary of key facts about Comet 17P/Holmes [tip: you can also create a Quick Access page for this data if you access it frequently and would like to have a simpler view]:

05h 59m 44s
+46° 56’ 20”
  • 17P/Holmes is above the horizon from Greenwich, United Kingdom [change].
  • It is visible looking in the North-West direction at an altitude of 28° above the horizon.
  • Given its current magnitude, 17P/Holmes is visible only through long exposure photography.
  • See also 17P/Holmes rise and set times.
  • 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.

Additional information about Comet 17P/Holmes available on TheSkyLive:

Available Resources

Comet 17P/Holmes Position and Finder Charts

Below we provide Comet 17P/Holmes 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.

Map showing Comet 17P/Holmes in Auriga on October, 18 2021
Field of view: 50x30 degrees
View fullscreen
Map showing Comet 17P/Holmes in Auriga on October, 18 2021
Field of view: 10x6 degrees
View fullscreen
 = visible to the naked eye
 = binocular, brighter than 10th magnitude
= current altitude ≥ 30°   = current altitude < 30°   = below the horizon
Location: Greenwich, United Kingdom [change]

Higher precision deep sky finder chart, 60 arcmin wide, showing where Comet 17P/Holmes is right now. Click on the image to see a more detailed fullscreen tracker view.

RA: 05h 59m 44s
Dec: +46° 56’ 20”
Deep sky finder chart for Comet 17P/Holmes
Field of view: 60x40 arcmins
View fullscreen

Also check out Where is Comet 17P/Holmes?, a page that provides all the information needed to find Comet 17P/Holmes in the sky and additional links to sky charts.

Comet 17P/Holmes Distance from Earth

The distance of Comet 17P/Holmes from Earth is currently 325,598,291 kilometers, equivalent to 2.176490 Astronomical Units. Light takes 18 minutes and 6.0790 seconds to travel from Comet 17P/Holmes and arrive to us.

18 minutes and 6.0790 seconds

The following chart shows the distance of Comet 17P/Holmes 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.

Distance of Comet 17P/Holmes from Earth between January 2013 and December 2100

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 17P/Holmes from Earth is also available as a real time updated value in the Live Position and Data Tracker.

Closest approach of Comet 17P/Holmes to Earth

Between January 2013 and December 2100, the closest approach of Comet 17P/Holmes to Earth happens on Thu Aug 20 2048 at a distance of 1.146457 Astronomical Units, or 171,507,503 kilometers:

Thu Aug 20 2048

NOTE: values for the closest approach are computed with a sampling interval of 1 day.

Comet 17P/Holmes brightness

The current visual magnitude of Comet 17P/Holmes is 17.42.


The observed magnitude and coma diameter values are derived from the Comet Observers Database by averaging the values reported in recent observations (more recent than 4 days), when available. The Estimated Magnitude comes from the JPL Horizons ephemerides service and might be inaccurate given the highly dynamic and unpredictable behavior of comets. When available, please refer to the Observed Magnitude value and consider the Estimated 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.

The following chart is the predicted light curve (visual magnitude as a function of time) of Comet 17P/Holmes, 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.

Predicted magnitude of Comet 17P/Holmes between January 2013 and December 2100

Comet 17P/Holmes rise and set times

Location: Greenwich, United Kingdom [change]
Latitude: 51° 28’ 47” N
Longitude: 0° 00’ 00” E
Timezone: Europe/London

Comet 17P/Holmes is circumpolar and transits at 04:12 UTC (altitude: 85.5°)

The rise and set times are defined as the time at which the upper limb of Comet 17P/Holmes touches the horizon, considering the effect of the atmospheric refraction. As the atmospheric conditions cannot be modeled precisely the times reported here should be considered correct with an approximation of few minutes.

Comet 17P/Holmes Orbital Elements

The following table lists the orbital elements of Comet 17P/Holmes at epoch 20 April 2015 00:00 UTC (JD: 2457133.5). Source: JPL Small-Body Database

Element Symbol Value
Orbit eccentricity e 0.43171430
Orbit inclination i 19.09187460°
Perihelion distance q 2.05728827 AU
307,765,946 km
Aphelion distance Q 5.18304266 AU
775,372,147 km
Semi-major axis a 3.62016547 AU
541,569,046 km
Orbital period period 6.8900 years
2,515.8866 days
Date of perihelion transit Tp 2014-Mar-27 13:21:02
2,456,744.0563 JD
Next perihelion transit 2021-Feb-14 10:37
2,459,259.9429 JD
Argument of perihelion peri 24.552159441537°
Longitude of the ascending node node 326.7637494977°
Mean anomaly M 55.725778684954°
Mean motion n 0.14309071°/day

Visualization of Comet 17P/Holmes Orbit

This 3d orbit diagram is a feature of our 3D Solar System Simulator and shows the orbit of Comet 17P/Holmes with respect of the Sun and the orbits of the major planets. The position of Comet 17P/Holmes 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 17P/Holmes
View Comet 17P/Holmes in the 3D Solar System Simulator

Comet 17P/Holmes 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. Click on each row of the table to locate Comet 17P/Holmes in our Online Planetarium at the chosen date.

Date Right AscensionR.A. DeclinationDec. MagnitudeMag Constellation
2021 Oct 11 05h 57m 24s +46° 12’ 36” 17.40 Auriga
2021 Oct 12 05h 57m 50s +46° 18’ 33” 17.40 Auriga
2021 Oct 13 05h 58m 14s +46° 24’ 29” 17.41 Auriga
2021 Oct 14 05h 58m 36s +46° 30’ 24” 17.41 Auriga
2021 Oct 15 05h 58m 54s +46° 36’ 15” 17.41 Auriga
2021 Oct 16 05h 59m 12s +46° 42’ 06” 17.42 Auriga
2021 Oct 17 05h 59m 26s +46° 47’ 56” 17.42 Auriga
2021 Oct 18 05h 59m 39s +46° 53’ 43” 17.42 Auriga
2021 Oct 19 05h 59m 49s +46° 59’ 26” 17.42 Auriga
2021 Oct 20 05h 59m 58s +47° 05’ 08” 17.43 Auriga
2021 Oct 21 06h 00m 03s +47° 10’ 47” 17.43 Auriga
2021 Oct 22 06h 00m 07s +47° 16’ 23” 17.43 Auriga
2021 Oct 23 06h 00m 09s +47° 21’ 56” 17.44 Auriga
2021 Oct 24 06h 00m 07s +47° 27’ 27” 17.44 Auriga