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🌎  Greenwich, United Kingdom [change]

Comet C/2021 A2

Comet C/2021 A2 is currently in the constellation of Cygnus. The current Right Ascension of Comet C/2021 A2 is 19h 54m 48s and the Declination is +59° 42’ 16” (topocentric coordinates computed for the selected location: Greenwich, United Kingdom [change]). The current estimated magnitude of Comet C/2021 A2 is 22.80 (JPL).

Summary of key facts about Comet C/2021 A2 [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]:

19h 54m 48s
+59° 42’ 16”
  • C/2021 A2 is above the horizon from Greenwich, United Kingdom [change].
  • It is visible looking in the North-East direction at an altitude of 40° above the horizon.
  • Given its current magnitude, C/2021 A2 is visible only through long exposure photography.
  • See also C/2021 A2 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 C/2021 A2 available on TheSkyLive:

Available Resources

Comet C/2021 A2 Position and Finder Charts

Below we provide Comet C/2021 A2 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 C/2021 A2 in Cygnus on September, 28 2022
Field of view: 50x30 degrees
View fullscreen
Map showing Comet C/2021 A2 in Cygnus on September, 28 2022
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 C/2021 A2 is right now. Click on the image to see a more detailed fullscreen tracker view.

C/2021 A2
RA: 19h 54m 48s
Dec: +59° 42’ 16”
Deep sky finder chart for Comet C/2021 A2
Field of view: 60x40 arcmins
View fullscreen

Also check out Where is Comet C/2021 A2?, a page that provides all the information needed to find Comet C/2021 A2 in the sky and additional links to sky charts.

Comet C/2021 A2 Distance from Earth

The distance of Comet C/2021 A2 from Earth is currently 969,271,672 kilometers, equivalent to 6.479181 Astronomical Units. Light takes 53 minutes and 53.1423 seconds to travel from Comet C/2021 A2 and arrive to us.

53 minutes and 53.1423 seconds

The following chart shows the distance of Comet C/2021 A2 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 C/2021 A2 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 C/2021 A2 from Earth is also available as a real time updated value in the Live Position and Data Tracker.

Closest approach of Comet C/2021 A2 to Earth

Between January 2013 and December 2100, the closest approach of Comet C/2021 A2 to Earth happens on Wed Feb 3 2021 at a distance of 0.506733 Astronomical Units, or 75,806,248 kilometers:

Wed Feb 3 2021

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

Comet C/2021 A2 brightness

The current visual magnitude of Comet C/2021 A2 is 22.80.


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 C/2021 A2, 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 C/2021 A2 between January 2013 and December 2100

Comet C/2021 A2 rise and set times

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

Comet C/2021 A2 is circumpolar and transits at 19:24 UTC (altitude: 81.8°)

The rise and set times are defined as the time at which the upper limb of Comet C/2021 A2 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 C/2021 A2 Orbital Elements

The following table lists the orbital elements of Comet C/2021 A2 at epoch 20 February 2021 00:00 UTC (JD: 2459266.5). Source: JPL Small-Body Database

Element Symbol Value
Orbit eccentricity e 0.99452815
Orbit inclination i 106.97835893°
Perihelion distance q 1.41297511 AU
211,378,068 km
Aphelion distance Q 515.03952623 AU
77,048,816,605 km
Semi-major axis a 258.22625067 AU
38,630,097,337 km
Orbital period period 4,149.6244 years
1,515,650.3047 days
Date of perihelion transit Tp 2021-Jan-22 15:13:12
2,459,237.1342 JD
Next perihelion transit 6170-Oct-08 22:31
3,974,887.4389 JD
Argument of perihelion peri 338.84903384462°
Longitude of the ascending node node 125.23825155612°
Mean anomaly M 0.0069750251957052°
Mean motion n 0.00023752°/day

Visualization of Comet C/2021 A2 Orbit

This 3d orbit diagram is a feature of our 3D Solar System Simulator and shows the orbit of Comet C/2021 A2 with respect of the Sun and the orbits of the major planets. The position of Comet C/2021 A2 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!

Comet C/2021 A2 15 Days Ephemeris

The following table lists the ephemerides of Comet C/2021 A2 computed for the past and next 7 days, with a 24 hours interval. Click on each row of the table to locate Comet C/2021 A2 in our Online Planetarium at the chosen date.

Date Right AscensionR.A. DeclinationDec. MagnitudeMag Constellation
2022 Sep 21 19h 57m 47s +61° 04’ 03” 22.76 Draco
2022 Sep 22 19h 57m 17s +60° 53’ 20” 22.76 Draco
2022 Sep 23 19h 56m 51s +60° 42’ 34” 22.77 Draco
2022 Sep 24 19h 56m 26s +60° 31’ 46” 22.78 Draco
2022 Sep 25 19h 56m 02s +60° 20’ 56” 22.78 Draco
2022 Sep 26 19h 55m 38s +60° 10’ 04” 22.79 Draco
2022 Sep 27 19h 55m 18s +59° 59’ 08” 22.79 Draco
2022 Sep 28 19h 54m 57s +59° 48’ 12” 22.80 Cygnus
2022 Sep 29 19h 54m 39s +59° 37’ 14” 22.80 Cygnus
2022 Sep 30 19h 54m 23s +59° 26’ 16” 22.81 Cygnus
2022 Oct 01 19h 54m 07s +59° 15’ 15” 22.81 Cygnus
2022 Oct 02 19h 53m 53s +59° 04’ 14” 22.82 Cygnus
2022 Oct 03 19h 53m 39s +58° 53’ 13” 22.83 Cygnus
2022 Oct 04 19h 53m 29s +58° 42’ 11” 22.83 Cygnus