The Brightest Comets of 2020 and 2021

~4 min

This year, despite all the turmoil, has still been a great one for any comet-lover. In today’s article, we’ll tell you about one more comet you can catch before the year is over, remember the most spectacular comets of 2020, and make predictions about the brightest comets of 2021.

One More Comet for 2020!

As 2020 is not over yet, we’ll start with the comet that you can see this December. C/2020 S3 (Erasmus) was discovered on September 17, 2020, by a South African astronomer Nicolas Erasmus. It’s a long-periodic comet with an orbital period of about 1,800 years. When the comet came close to the Earth last time, two millennia ago, it went unnoticed because the telescope hadn't been invented yet.

Erasmus is quite a bright comet that could reach a peak magnitude of 5.7, but you need to hurry if you want to catch it. On December 12, 2020, the comet will reach perihelion – its closest point to the Sun. From that point on, it will be unobservable, as it will be obscured by the Sun’s glare. Right now, you can try to spot C/2020 S3 (Erasmus) with a pair of binoculars or a small telescope. The easiest way to locate the comet is to use the Star Walk 2 app – just tap the magnifier icon and type “Erasmus” in the search field.

Around Christmas time, the comet will drop too low in the sky and won’t be observable from the ground. However, NASA/ESA's Solar Heliospheric Observatory spacecraft SOHO will be able to watch Erasmus leave the vicinity of our planet, as the comet will get into the field of view of SOHO’s LASCO C2 coronagraph.

Most Memorable Comets of 2020

The undisputed queen among the comets of 2020 was C/2020 F3 (NEOWISE). Since its discovery in March 2020, more and more observers got interested in the comet, as it was getting brighter and closer to the Earth. In the course of three months, it brightened from magnitude 17 to magnitude 1 and was clearly visible with the naked eye. As a result, comet NEOWISE probably became one of the most photographed comets in history. If you also managed to take its photo, give yourself a thumbs up, as NEOWISE won’t be back for almost 7,000 years.

The next brightest comet was C/2020 F8 (SWAN), also discovered in March 2020. With its greenish coma and a 10-million-mile-long tail, the comet provided a splendid show, especially for observers from the Southern hemisphere. At the end of April, it shined in the sky with a magnitude 5 and was bright enough to be seen with the naked eye. Unfortunately, shortly after that, the comet started decreasing in brightness and even breaking up.

Number three is taken by the long-period comet C/2019 U6 (LEMMON). It was discovered by the Mount Lemmon Survey in October 2019. In June 2020, the comet reached a visual magnitude of 6 and was visible with binoculars or even the naked eye in dark clear skies. It wasn’t nearly as bright as comet NEOWISE, but still provided a breathtaking view if you managed to find it.

Comets to Catch in 2021

Here’s a small list of upcoming comets that might be worthy of your attention next year.

In June 2021, we’ll be visited by a short-period comet 7P/Pons–Winnecke which has an orbital period of about 6 years. This comet has been known for more than 200 years since its discovery in 1819 by a French astronomer Jean Louis Pons. 7P/Pons–Winnecke will get quite close to the Earth (about 0.44 AU) in June, but it won’t be sufficient to make it a bright object in our skies. It will reach a visual magnitude of about 10 and will be best visible through telescopes from the Southern Hemisphere.

Another short-period comet, 15P/Finlay, will fly by our planet in July 2021, brightening up to magnitude 10. This comet was discovered in 1886 by a South African astronomer William Henry Finlay. An interesting fact: of all the short-period comets, 15P/Finlay has one of the smallest minimum orbit intersection distances (MOID) with the orbit of the Earth. In 2060, it will pass roughly 0.04 AU from us, which is only about 6.0 million km. This will be one of the closest comet approaches to our planet in history! Alas, we’ll have to wait a bit (to put it mildly).

You might have heard about this last one. During the famous Rosetta mission in 2014, the lander module Philae successfully landed on a comet for the first time. The comet was 67P/Churyumov–Gerasimenko. It is named after two Soviet astronomers who discovered it in 1969 – Klim Churyumov and Svetlana Gerasimenko. This short-period comet will be visiting the Earth next year and will get closest to us in November – it will be about 0.41 AU away. It is predicted to reach 9th or even 8th magnitude, which will make it observable through binoculars.

For now, the year 2021 doesn’t seem very promising in terms of super-bright comets. But let’s hope for the best – in 2020, nobody expected NEOWISE to make such a memorable appearance. Keep looking at the sky!

Updated January 16, 2021: Comet Leonard

A newly discovered non-periodic comet C/2021 A1 (Leonard) will visit us by the end of 2021. It will get closest to the Earth and will be best visible on December 12. According to estimates, it might brighten up to magnitude 1.5. Observers located in the northern mid-latitudes can start looking for the comet already in September, while observers from the Southern hemisphere should wait until the second half of December. Comet Leonard was discovered on January 3, 2021, by an American astronomer Gregory J. Leonard at the Mount Lemmon Observatory in Arizona, USA. You can learn more about the comet in our article.