Comet C/2021 A1 (Leonard) will make its closest approach to the Earth on 12 December, at a distance of of 0.23 AU.
From Fairfield on the day of perigee it will not be observable – it will reach its highest point in the sky during daytime and will be no higher than 3° above the horizon at dawn.
The events that comprise the 2021–2022 apparition of C/2021 A1 (Leonard) are as follows:
| Date | Event |
| 12 Dec 2021 | Comet C/2021 A1 (Leonard) passes perigee |
| 03 Jan 2022 | Comet C/2021 A1 (Leonard) passes perihelion |
The table below lists the times when C/2021 A1 (Leonard) will be visible from Fairfield day-by-day through its apparition:
| Date | Constellation | Comet visibility |
| 21 Nov 2021 | Canes Venatici | Visible from 02:29 until 05:36 Highest at 05:36, 56° above E horizon |
| 23 Nov 2021 | Canes Venatici | Visible from 02:29 until 05:38 Highest at 05:38, 56° above E horizon |
| 25 Nov 2021 | Canes Venatici | Visible from 02:29 until 05:40 Highest at 05:40, 56° above E horizon |
| 27 Nov 2021 | Canes Venatici | Visible from 02:30 until 05:42 Highest at 05:42, 56° above E horizon |
| 29 Nov 2021 | Coma Berenices | Visible from 02:34 until 05:44 Highest at 05:44, 55° above E horizon |
| 01 Dec 2021 | Canes Venatici | Visible from 02:43 until 05:46 Highest at 05:46, 53° above E horizon |
| 03 Dec 2021 | Bootes | Visible from 02:59 until 05:48 Highest at 05:48, 50° above E horizon |
| 05 Dec 2021 | Bootes | Visible from 03:26 until 05:49 Highest at 05:49, 45° above E horizon |
| 07 Dec 2021 | Bootes | Visible from 04:10 until 05:51 Highest at 05:51, 36° above E horizon |
| 09 Dec 2021 | Serpens Caput | Visible from 05:17 until 05:53 Highest at 05:53, 24° above E horizon |
| 11 Dec 2021 | Ophiuchus | Not observable |
| 13 Dec 2021 | Ophiuchus | Not observable |
| 15 Dec 2021 | Sagittarius | Not observable |
| 17 Dec 2021 | Sagittarius | Not observable |
| 19 Dec 2021 | Sagittarius | Not observable |
| 21 Dec 2021 | Microscopium | Not observable |
| 23 Dec 2021 | Microscopium | Not observable |
| 25 Dec 2021 | Microscopium | Not observable |
| 27 Dec 2021 | Microscopium | Not observable |
| 29 Dec 2021 | Piscis Austrinus | Not observable |
| 31 Dec 2021 | Piscis Austrinus | Not observable |
A more detailed table of C/2021 A1 (Leonard)'s position on each night is available here. A diagram of the orbit of C/2021 A1 (Leonard) is available here.
Finder chart
The chart below shows the path of C/2021 A1 (Leonard) over the course of its apparition, as calculated from the orbital elements published by the Minor Planet Center (MPC). It is available for download, either on dark background, in PNG, PDF or SVG formats, or on a light background, in PNG, PDF or SVG formats. It was produced using StarCharter.
Comet brightnesses
Comets are intrinsically highly unpredictable objects, since their brightness depends on the scattering of sunlight from dust particles in the comet's coma and tail. This dust is continually streaming away from the comet's nucleus, and its density at any particular time is governed by the rate of sublimation of the ice in the comet's nucleus, as it is heated by the Sun's rays. It also depends on the amount of dust that is mixed in with that ice. This is very difficult to predict in advance, and can be highly variable even between successive apparitions of the same comet.
In consequence, while the future positions of comets are usually known with a high degree of confidence, their future brightnesses are not. For most comets, we do not publish any magnitude estimates at all. For the few comets where we do make estimates, we generally prefer the BAA's magnitude parameters to those published by the Minor Planet Center, since they are typically updated more often.
No estimate for the brightness of comet C/2021 A1 (Leonard) is currently available.
The comet's position at perigee will be:
| Object | Right Ascension | Declination | Constellation | Magnitude |
| Comet C/2021 A1 (Leonard) | 17h06m10s | 1°24'S | Ophiuchus | 3.6 |
The coordinates are given in J2000.0.
The sky on 12 Dec 2021
| The sky on 12 December 2021 | ||||||||||||||||||||||||||||||||||
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70% 8 days old |
All times shown in EST.
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Source
This event was automatically generated on the basis of orbital elements published by the Minor Planet Center (MPC) , and is updated whenever new elements become available. It was last updated on 02 Jan 2024.
Image credit
© Andy Roberts 1997. Pictured comet is C/1995 O1 Hale-Bopp.