Comet Leonard brightens

There’s a new comet on the block – Comet Leonard. It’s not bright, so you won’t see it without good equipment, but for the keen observers and photographers it’s looking promising in the early morning sky.

It was discovered at the beginning of 2021 from Mt Lemmon in the US by Gregory Leonard, hence the comet’s name. At the time it was faint and distant, but now it is approaching the Sun and getting brighter all the time although it won’t become a show-stopper that has everyone in the street pointing at it. More the sort of thing that you’ll need to drive out to some country layby and spend some time searching for, hoping not to attract too much attention from passing traffic as you do so. But this picture from Dave Eagle shows what you can do with the right equipment at 4 am!

Comet C/2021 A1 Leonard, photographed by Dave Eagle with 120 mm refractor on 25 November 2021. The galaxies NGC 4631 and 4656 are also shown. The brightest stars in this view are magnitude 10, which is about 100 times fainter than readily visible with the naked eye.

Currently (late November 2021) the comet is in the constellation of Canes Venatici and it rises around midnight, so it is reasonably well placed by about 2 am although later in the morning is better. Its magnitude compared with stars is about 8, which is visible with good binoculars in a dark sky but not from a light-polluted environment.

It reaches its closest to the Sun on 12 December, when it may be about magnitude 4, but at that time it will be quite close to the Sun and not easily observed from the UK. In the next week or two it will be brightening and moving lower in the early morning sky, so the optimum time to observe it will probably be in the first week of December when it is brightening and still high enough to be in a dark sky at around 5:30 UT in the east not far from the bright star Arcturus.

A processed stack of photos taken by our Comet Section Director, Stuart Atkinson, on the morning of 2 December, shows the comet approaching the globular cluster M3.

Our Comet Section Director, Stuart Atkinson, gives further information here. For the current position of the comet, the Heavens Above website will provide finder charts and updated positions at any time. Go to and click on Comets. The comet is sufficiently distant that you don’t need to enter your home location for this, but to obtain satellite information, such as timings of the International Space Station, you do need to enter your location. The ISS is currently making a series of evening passes over the UK.

Comet positions and elements from Central Bureau for Astronomical Telegrams

The following predictions of positions and magnitudes were issued on 2 December. Note that they are for the standard epoch of 2000.0, suitable for plotting on maps, and the positions for the current date will be slightly different.

Date    TT    R. A. (2000) Decl.        Mag.
2021 12 02    13 30.12   +29 16.7       6.6
2021 12 04    13 51.87   +27 23.5       6.1
2021 12 06    14 20.66   +24 25.7       5.6
2021 12 08    14 59.04   +19 39.0       5.1
2021 12 10    15 49.15   +12 06.2       4.6
2021 12 12    16 49.92   +01 32.3       4.3
2021 12 14    17 54.38   -09 57.9       4.2
2021 12 16    18 52.73   -19 15.4       4.3

The elements of the comet’s orbit, for insertion into sky prediction programs, are:

     Epoch = 2022 Jan. 21.0 TT
     T = 2022 Jan.  3.29850 TT        Peri. = 225.09198
     e = 1.0000279                    Node  = 255.89560 2000.0
     q = 0.6152614 AU                 Incl. = 132.68630