Comets are icy/rocky bodies (usually a few kilometers in size) that originate from the regions beyond Neptune; remnant material from the formation of our solar system.  Their characteristic wispy tails are formed as some of their icy crust and dust boils off as they heat-up as they fall inward through our solar systems toward the Sun. Some comets  have established stable orbits around the Sun and return periodically (ie Halley’s Comet every 86 years) while others make a one-time passage through our solar system as they whip around the Sun and are then flung outward with sufficient velocity never to return. What we see as meteors is the earth traveling through the dust and debris trail left behind by comets, the dust particles burning up as they impact the earth’s atmosphere.

Many people seem to confuse comets with meteors in the sense that they think that cometary appearances are very fleeting events.  While this is certainly true of meteors where they literally come and go in the blink of an eye, Comets are much more lasting events, which can be viewed for weeks if not months with the aid of binoculars or small telescopes.  There are usually a half-dozen or more comets every year that are viewable to the enterprising observer, and every few years there is a comet that brightens to the naked-eye visibility and garners much publicity.  

Comets are usually identified by the year they are first observed and the name of the Observatory, Facility or person that made the discovery. So for the case of Comet 2023 A3 Tsuchinshan-ATLAS, it was co-discovered in 2023 by the Tsuchinshan Observatory in China and the ATLAS (Asteroid Terresestrial-impact Last Alert System) early-warning system.

The “A3” designates the month the comet was discovered. Each month is split in half with “A” being the first-half of January and “B” the second-half while “C” is the first-half of February and “D” is the second-half, and so on (with “I” not being used). The number designates the order in which the Comet was discovered in that particular half-month period. Thus “A3” means that this comet was the third comet to be discovered in the first-half of January 2023.

If the comet has a “P” designation it means that it is a “Periodic Comet” – one that has previously been observed with a well defined orbit. Halley’s Comet “1/P Halley“ which appears every 72-80 years is the best known example of a periodic comet.

In regards to the published magnitude values for Comets, and for that matter all extended objects such as Nebulae and Galaxies, the magnitude values are integrated values. That means the brightness is calculated on the total light emitted (or reflected) over its entire surface area. For stars the light is emitted from a single concentrated point while for extended objects, like comets, it includes not only the bright nucleus but also the extended tail – if any. Thus a comet or galaxy may appear dimmer than the published magnitude value might suggest as the total emitted light is spread over a larger area.

Below are photos of some of the comets I have observed over the years and many of the photos show what can be achieved using nothing more than a simple camera or cellphone.

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For the better part of a year the approach of comet C/2023 A3 Tsuchinshan-ATLAS has been eagerly anticipated as it was projected to reach “Naked Eye” visibility. As shown in the photos below it didn’t disappoint and is the best “Naked Eye” comet since Comet NEOWISE in 2020 and is being called the most photographed comet in history.