COMET RESOURCE CENTER
NOTABLE UPCOMING COMETS
|Last updated: March 23, 2021
For planning purposes, on this page I will list the incoming comets that are expected to become moderately bright or otherwise notable within the next one to two years, and which I expect to add to my tally (if I haven't already). I don't intend this list to be exhaustive, but instead will focus on those comets that are worthy of attention from sky-watchers and other interested people (including, certainly, students) who would not normally be considered "comet astronomers." I plan to update this page every one to two months and/or as necessary.
The "long-range" comets listed at the end of this page are, as implied, mentioned here primarily for long-range planning purposes.
COMET 7P/PONS-WINNECKE (Perihelion 2021 May 27)
This long-known comet has a rather storied history, which includes a series of close approaches to Earth during the early decades of the 20th Century, although since it has been perturbed into a larger orbit it can no longer make such approaches. The 2021 return is the most favorable one it will have had in several decades, with a minimum distance from Earth of 0.44 AU taking place in mid-June, and it should reach 10th or 11th magnitude. It has already been recovered as a very faint object in early January 2020.
COMET 6P/d'ARREST (Perihelion 2021 September 27)
After its favorable return in 2008 (no. 435) I missed this comet entirely during its unfavorable return in 2015, although apparently some observers in the southern hemisphere managed to detect it as a faint object. The return in 2021 is moderately favorable, similar to that of 1982 (no. 51) during which it reached close to 9th magnitude. The comet remains in the evening sky, at a somewhat high southerly declination (-20 degrees to -30 degrees) throughout the course of the apparition.
COMET 67P/CHURYUMOV-GERASIMENKO (Perihelion 2021 November 2)
After its rather mediocre return in 2009 (no. 444) this comet returned again, under slightly better but still mediocre circumstances, in 2015 (no. 577), and reached 12th magnitude. This was the return where it was visited and studied by ESA's Rosetta mission, and I discuss this in detail in the comet's "Ice and Stone 2020" "Comet of the Week" presentation. The viewing geometry for the return in 2021 is very favorable, similar to that of 1982 (no. 53) where it reached 9th magnitude and I could detect it with 10x50 binoculars and see some dramatic tail structure telescopically. The comet remains well placed for observation for several months and is closest to Earth (0.42 AU) a week and a half after perihelion passage.
COMET LEONARD C/2021 A1 (Perihelion 2022 January 3)
The first comet discovery of 2021 was found exactly one year before its perihelion passage, which takes place at a heliocentric distance of 0.615 AU. It will be visible in the northern hemisphere's morning sky during the last few months of 2021 before passing between Earth and the sun on December 12, passing 0.23 AU from Earth as it does so. Afterwards it is visible low in the evening sky, passing only 0.029 AU from Venus on December 18, and then remains visible in the southern hemisphere's evening sky through the latter part of January 2022 as it passes through perihelion and subsequently recedes from Earth on the far side of the sun. While predicting the brightness of a long-period comet is always problematical, it seems reasonably conceivable that Comet Leonard could achieve naked-eye brightness during its run-up to perihelion, especially since it is apparently not a first-time visitor from the Oort Cloud. When it passes close to Earth it will be appearing at a high phase angle (up to 160 degrees), and if the comet has a high dust content there is a possibility of a distinct enhancement of its brightness around that time due to forward scattering of sunlight.
COMET 19P/BORRELLY (Perihelion 2022 February 1)
I've managed to observe this comet at all of its recent returns, including the mediocre one in 2008 (no. 436) and the very unfavorable one in 2015 (no. 585), when I saw it a couple of times as a very faint object over four months past perihelion. The 2022 return is the best one it will have had in over two decades, being somewhat similar to its return in 1981 (no. 43), the first time I observed it and during which it reached 10th magnitude. The comet is deep in southern skies (declination south of -50 degress) until early November 2021 and should become visually detectable from the southern hemisphere during that period; it comes northward after that and I expect to pick it up in the evening sky before the end of 2021 and be able to follow it until April or May 2022.
COMET 12P/PONS-BROOKS (Perihelion 2024 April 21)
This "classical" Halley-type comet (period 70 years) last returned in 1954, four years before I was born. The viewing geometry in 2024 is, unfortunately, rather unfavorable, as during the run-up to perihelion the comet remains on the far side of the sun from Earth and is only visible for a brief period of time in the northwestern sky after dusk, at a small elongation (37 degrees in mid-March, shrinking to 28 degrees by month's end and to 23 degrees by perihelion). Despite the poor viewing geometry, the comet is intrinsically rather bright, and should reach a peak brightness close to 5th magnitude. After perihelion the comet travels southward and is visible from the southern hemisphere as it recedes and fades.
UPDATE (June 28, 2020): Comet Pons-Brooks was recovered on June 10, 2020 -- almost four years before perihelion passage -- by a team of astronomers led by Matthew Knight utilizing the Lowell Discovery Telescope in Arizona (with confirming images obtained on June 17). The comet's heliocentric distance at the time of its recovery was 11.93 AU, and it appeared as a very faint object near 23rd magnitude, with a short tail indicating that it is already active.
COMET 13P/OLBERS (Perihelion 2024 June 30)
This other "classical" Halley-type comet (period 68 years) last returned in 1956, two years after the above comet and two years before I was born. Also as with the above comet, the viewing geometry remains relatively poor, with the comet's remaining on the far side of the sun from Earth; on the other hand, it is almost identical to the viewing geometry in 1956. It remains in the northern hemisphere's evening sky throughout the period of prime visibility, albeit at a small elongation (dropping below 30 degrees in early May, to a minimum of 25.5 degrees in early June before increasing back to 30 degrees by perihelion to a maximum of 39 degrees in August). Based upon the reported brightnesses in 1956, the comet should reach a peak brightness between 6th and 7th magnitude.
Around mid-April 12P/Pons-Brooks and 13P/Olbers will be located some 15 degrees from each other, the latter comet being higher (to the east and north) of the former one.
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