A new ‘green’ comet for 2023

There’s a new comet in the sky which is already creating a flurry of interest among amateur astronomers, visible at the end of January and early February 2023. Don’t get your hopes up too high, but just be pleasantly surprised if you manage to spot it with binoculars and glimpse its tail.But don’t expect to see it looking green as the media hype says!

Updated 30 January 2023

Read the update by Stuart Atkinson, our Comet Section Director, with much more information about what you can see despite the media hype!

The comet is called C/2022 E3 ZTF, and it gets this jolly name from the time it was discovered and the instrument used to locate it. It is currently easily visible using binoculars in the evening sky. By the end of January it will be fairly close to Polaris, the Pole Star, so it should be easy to find.

Photographs (see below) show it with a green centre, which is quite common in comets due to the molecule cyanogen, (CN)2. However, even with a large telescope you are unlikely to see the colour. That’s the way it is, but the clickbait stories won’t tell you that.

Observers equipped with even small telescopes and cameras (and good tracking mounts) are taking great pictures of the comet, such as the one from Brian O’Halloran in Waterford, Ireland, below. You will need a chart to be able to find it, but it’s currently brighter than magnitude 5 – still not brilliant, but a good binocular object and just about glimpsable with the naked eye in a good, dark sky.

The comet will be at its closest to Earth on 2 February. Here are positions calculated by Chris Marriott’s SkyMap software for midnight (0 hours) on the dates shown. The distance shown is distance from the Earth in astronomical units (the Earth–Sun distance) where 1 AU = 149,600,000 km. At its closest, the comet will be 48.5 million km from Earth.

Many news stories are saying that the comet was last seen during the Neolithic period. However, the orbital details don’t confirm this, and show it having a nearly parabolic orbit. The best we can say is that its period is indeterminate.

Ephemeris of comet C/2022 E3 ZTF

Date Top R.A. Top Dec Mag Distance
20 Jan 2023 15h 36m 39.4s +49° 01′ 56″ 6.5 0.5056
21 Jan 2023 15h 33m 20.0s +51° 08′ 03″ 6.4 0.4792
22 Jan 2023 15h 29m 10.7s +53° 28′ 33″ 6.3 0.4535
23 Jan 2023 15h 23m 52.0s +56° 05′ 17″ 6.2 0.4286
24 Jan 2023 15h 16m 53.2s +59° 00′ 03″ 6.1 0.4047
25 Jan 2023 15h 07m 23.0s +62° 14′ 25″ 5.9 0.3821
26 Jan 2023 14h 53m 49.8s +65° 48′ 57″ 5.8 0.3610
27 Jan 2023 14h 33m 16.4s +69° 41′ 55″ 5.7 0.3416
28 Jan 2023 13h 59m 26.3s +73° 45′ 29″ 5.6 0.3245
29 Jan 2023 12h 58m 22.6s +77° 35′ 08″ 5.5 0.3098
30 Jan 2023 11h 07m 36.0s +80° 01′ 50″ 5.5 0.2981
31 Jan 2023 08h 47m 40.9s +79° 14′ 18″ 5.4 0.2897
01 Feb 2023 07h 11m 06.9s +75° 17′ 43″ 5.4 0.2850
02 Feb 2023 06h 18m 59.3s +69° 50′ 06″ 5.4 0.2840
03 Feb 2023 05h 49m 28.8s +63° 51′ 03″ 5.5 0.2869
04 Feb 2023 05h 31m 09.7s +57° 49′ 19″ 5.5 0.2936
05 Feb 2023 05h 18m 53.7s +52° 00′ 49″ 5.6 0.3038
06 Feb 2023 05h 10m 12.4s +46° 34′ 43″ 5.7 0.3172
07 Feb 2023 05h 03m 47.2s +41° 35′ 39″ 5.8 0.3333
08 Feb 2023 04h 58m 53.6s +37° 05′ 05″ 6.0 0.3519
09 Feb 2023 04h 55m 04.2s +33° 02′ 25″ 6.1 0.3725
10 Feb 2023 04h 52m 01.7s +29° 25′ 52″ 6.3 0.3948
11 Feb 2023 04h 49m 34.4s +26° 13′ 02″ 6.4 0.4185
12 Feb 2023 04h 47m 34.3s +23° 21′ 20″ 6.6 0.4435
13 Feb 2023 04h 45m 55.6s +20° 48′ 18″ 6.7 0.4694
14 Feb 2023 04h 44m 34.1s +18° 31′ 36″ 6.9 0.4961
15 Feb 2023 04h 43m 26.7s +16° 29′ 08″ 7.0 0.5235
16 Feb 2023 04h 42m 30.9s +14° 39′ 07″ 7.2 0.5515
17 Feb 2023 04h 41m 44.8s +12° 59′ 56″ 7.3 0.5800
18 Feb 2023 04h 41m 07.0s +11° 30′ 14″ 7.4 0.6088
 
2022e3_20230102_0523_ohalloran
Comet C/2022 E3 ZTF, photographed by Brian O’Halloran from Dunabrattin, Co. Waterford on 2 January 2023 at 05:23 UT. He used a Canon 250D camera and 81 mm refractor and a total exposure time of 30 minutes.
_DSC4965-75a
Comet C/2022 E3 ZTF, photographed with 72 mm refractor. A combination of 10 30-second exposures from Flackwell Heath, Bucks, by Robin Scagell. The stars are trailed as a result of the comet’s motion. North is to the left. The comet was visible with 10 x 30 binoculars.

Shown below are finder charts for the comet. Bear in mind that if you are observing before midnight, the comet will be close to the position for midnight on the following date.

eVscope-20230115-041928-01
View taken at 05:00 on 15 January by Jan Drozd using a 114 mm eVscope reflecting telescope.
_DSC5045-8
The comet as photographed from near High Wycombe using a 432 mm focal length lens on 27 January 2023

 

E3_ZTF_c
Track of the comet looking east during January and February 2023. The curved line indicates the horizon. Stars are shown to magnitude 6. Maps made using Chris Marriott’s SkyMap. Click to enlarge.
E3_ZTF_b
Track of the comet from 20 to 29 January 2023 through the constellations of Boötes, Draco, Ursa Minor and Camelopardalis. Stars shown to magnitude 8. Click to enlarge.
E3_ZTF_d
Detailed track of the comet from 31 January to 8 February 2023 through Cepheus and Auriga. Stars shown to magnitude 8. Click to enlarge.