Amateur astronomers may soon be able to see a comet that was initially spotted back in 2017.

Artist’s Impression of a comet pᴀssing through our solar system

Comet C/2017 K2 (PANSTARRS), abbreviated as K2 for short, was once the most distant active comet ever identified, a distinction it recently ceded to the megacomet Comet Bernardinelli-Bernstein, discovered last year. Nevertheless, even without a superlative, K2 is exceptional for its activity. The comet started spewing gas and dust in the extreme reaches of the solar system, although it is more normal for comets to awaken considerably closer to Jupiter’s orbit.

Five years later, the frozen body is now within reach of amateur astronomers on Earth. K2’s closest visit to Earth will occur on July 14, while its closest approach to the sun will occur on December 19.

The up-to-date image of Comet 2017 K2 Panstarrs.Courtesy Gerald Rhemann, Farm Tivoli, Namibia.

ᴀssuming K2 survives the arduous voyage and continues to shine, It is very much possible that small telescopes will soon be able to spot the comet.

It should brighten to magnitude 8 or even 7, still too dim for the unaided eye. Magnitude 6 stars are often visible to the naked eye in conditions of complete darkness. In order to see this comet with a telescope, you will also require locations free of light pollution.

The darker the skies, the better the distinction will be.

As the comet approaches, expert observatories may be able to determine the size of its nucleus. Early observations by the Canada–France–Hawaii Telescope (CFHT) indicated that K2’s nucleus might be between 18 and 100 miles (30 and 160 kilometers) wide (twice the size of Mount Everst); studies by the Hubble Space Telescope indicated that it could be as small as 11 miles (18 kilometers).

In 2017, Hubble imaging revealed that the coma (or fuzzy atmosphere) of the comet likely consists of oxygen, nitrogen, carbon dioxide, and carbon monoxide, all of which transformed from solid to gas when the comet warmed.

Comet C/2017 K2 (PANSTARRS) during its first voyage into the Solar System. The comet was detected midway between Saturn’s and Uranus’ orbits (Pluto is the furthest orbit visible in the image). (PH๏τo courtesy of A. Field/NASA/ESA/STScl)

NASA said at the time that an archive check of CFHT pH๏τos revealed K2 was active at least as far back as 2013 when it was between the orbits of Uranus and Neptune.

EarthSky wrote “Also, some observations detected an incredibly large tail, some 500,000 miles (800,000 km) long”.

However, any projections of comet activity are subject to change. Comets are prone to fragmenting or brightening unexpectedly as they approach the sun’s strong heat and gravity. This trait, however, makes them more intriguing to astronomers who want to understand how comets are formed.

So overall, it is possible that this comet will put on a magnificent show. To see this with an unaided eye, you may have to travel to a region with almost no light pollution and if you want to see it from the city then you will need a backyard telescope. 

Reference(s): EarthSky, NASA(archive)