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🌎 Location: Greenwich, United Kingdom [change]

Comet 17P/Holmes

Comet 17P/Holmes is currently in the constellation of Capricornus. The current Right Ascension of Comet 17P/Holmes is 21h 49m 57s and the Declination is -10° 04’ 06” (topocentric coordinates computed for the selected location: Greenwich, United Kingdom [change]). The current estimated magnitude of Comet 17P/Holmes is 16.31 (JPL).

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]:

21h 49m 57s
-10° 04’ 06”

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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 Capricornus on January, 19 2021
Field of view: 50x30 degrees
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Map showing Comet 17P/Holmes in Capricornus on January, 19 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: 21h 49m 57s
Dec: -10° 04’ 06”
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 437,948,796 kilometers, equivalent to 2.927507 Astronomical Units. Light takes 24 minutes and 20.8399 seconds to travel from Comet 17P/Holmes and arrive to us.

24 minutes and 20.8399 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 1.146193 Astronomical Units, or 171,468,036 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 16.31.


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

Today's Comet 17P/Holmes rise, transit and set times from Greenwich, United Kingdom [change] are the following (all times relative to the local timezone Europe/London):

Azimuth: 100.2°
Max altitude: 28.4°
Azimuth: 259.9°

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 18 December 2014 00:00 UTC (JD: 2457010.5). Source: JPL Small-Body Database

Element Symbol Value
Orbit eccentricity e 0.43176651
Orbit inclination i 19.09179895°
Perihelion distance q 2.05675906 AU
307,686,776 km
Aphelion distance Q 5.18237452 AU
775,272,194 km
Semi-major axis a 3.61956679 AU
541,479,485 km
Orbital period period 6.8900 years
2,515.2625 days
Date of perihelion transit Tp 2014-Mar-27 12:35:37
2,456,744.0247 JD
Next perihelion transit 2021-Feb-13 18:53
2,459,259.2873 JD
Argument of perihelion peri 24.524735127438°
Longitude of the ascending node node 326.76410674619°
Mean anomaly M 38.139595358267°
Mean motion n 0.14312621°/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 Jan 12 21h 33m 56s -12° 08’ 17” 16.31 Capricornus
2021 Jan 13 21h 35m 58s -11° 52’ 50” 16.31 Capricornus
2021 Jan 14 21h 37m 59s -11° 37’ 19” 16.31 Capricornus
2021 Jan 15 21h 40m 00s -11° 21’ 46” 16.31 Capricornus
2021 Jan 16 21h 42m 02s -11° 06’ 06” 16.31 Capricornus
2021 Jan 17 21h 44m 03s -10° 50’ 25” 16.31 Capricornus
2021 Jan 18 21h 46m 05s -10° 34’ 37” 16.31 Capricornus
2021 Jan 19 21h 48m 06s -10° 18’ 47” 16.31 Capricornus
2021 Jan 20 21h 50m 07s -10° 02’ 53” 16.31 Capricornus
2021 Jan 21 21h 52m 08s -09° 46’ 55” 16.31 Capricornus
2021 Jan 22 21h 54m 08s -09° 30’ 54” 16.31 Capricornus
2021 Jan 23 21h 56m 09s -09° 14’ 48” 16.31 Capricornus
2021 Jan 24 21h 58m 10s -08° 58’ 40” 16.31 Capricornus
2021 Jan 25 22h 00m 11s -08° 42’ 28” 16.31 Aquarius