Last year, Comet 46P/Wirtanen continued to put on a reasonable 5th magnitude show at the beginning of the year following on from from it’s 2018 perihelion. Also, long period comet Iwamoto (C/2018 Y1) reached magnitude 6. We also enjoyed around 50 new comet discoveries and 17 recoveries. Relative excitement ensued over interstellar comet 2I/Borisov. With all that activity not one of these comets resulted in a naked eye object or one that even became easily visible in binoculars.
So what’s in store for 2020? At the time of writing, forecasts suggest that enthusiasts may have to become resilient towards any high expectation. This year we are served up a small flurry of comets all of which remain within telescopic realm of visual brightness. [UPDATE: Comet C/2019 Y4 (ATLAS) may change all this!]
Newly discovered comet C/2019 Y4 (ATLAS) is a near-parabolic comet that was discovered last December by the Asteroid Terrestrial-impact Last Alert System survey in Hawaii. This object has the potential to become a truly great naked eye comet. Or.. it could fizzle out before it gets the chance to.
At the time of writing, the comet had brightened some 600-fold from 20th magnitude in December 2019 to 8th magnitude in March 2020. This is an unprecedented rate of increase and many astronomers believe that comet Atlas cannot maintain such a rate all the way to perihelion on 31 May.
Peak brightness predictions have varied greatly with some forecasting a whopping visual magnitude of -11 while other’s suggest a more conservative magnitude +2. Either way, most predictions fall within naked eye visibility.
For more information, diagrams and finder charts, visit our more detailed article on Comet C/2019 Y4 (ATLAS)
Short period comet 289P/Blanpain reaches closest approach to Earth on 10 January 2020 at a distance of 0.089 AU, however was predicted to reach around magnitude 15, this proved to worsen with actual observations peaking at mag. 18.
Comet 2017 T2 (PanSTARRS)
2017 T2 starts the year well placed for UK and northern hemisphere observers close to the zenith each evening in the constellation of Perseus. The comet passes the famous Perseus double cluster from 26-30 January, an opportunity for any astrophotographers out there.
The comet remains well placed for the first half of the year passing close to the pair of M81 & M82 galaxies in May. At the same time, observers will be battling with the ever looming light summer nights before it passes countless galaxies in Canes Venatici. By August, comet 2017 T2 will be sinking in to the twilight sky visible only in telescopes.
At the time of writing this comet is shining at magnitude 9.5 keeping it only visible through telescopes and good-sized binoculars.
This short period comet was discovered in 1981 by Ellen Howell. For UK observers this comet is a convenient evening object until it is lost in the summer twilight by June. It is better placed for Southern Hemisphere observers who may witness the object reaching 5th magnitude.
29P is an annual short period comet that has famously endured several outbursts over recent years. The comet is in solar conjunction through March and at opposition in October.
By the second half of 2020, 29P should be readily visible from the Northern hemisphere. At the time of writing, Comet 29P/Schwassmann-Wachmann is hovering around magnitude 14.5, however as said before this is always ‘one to watch’.