Comet C/2023 A3

“Comets are like cats: they have tails, and they do precisely what they want.” Davis H. Levy, Comets: Creators and Destroyers

A visitor from afar is in the neighborhood.  Comet C/2023 A3 ( Tsuchinshan-Atlas ), A3 for short, will be visible by the end of September in the morning sky.  Comet names tell us much about the comet.  The letter C means the comet is non-periodic.  Non-periodic comets originate in the Oort cloud.  They visit the inner solar system only once or they have an orbit that takes from 200 to many thousands of years to orbit the Sun.  The orbit of A3 around the Sun has been calculated to be 80,660 Years.  2023 is the year the comet was discovered and A3 means it was discovered in the first half of January and it was the third such object discovered in this same period.  Following tradition, comets are named for the person(s) and/or instruments/observatories that discovered them – Tsuchinshan is for the Purple Mountain Observatory (Zijinshan Astronomical Observatory) and ATLAS is the Asteroid Terrestrial-impact Last Alert System, at the Sutherland Observatory in South Africa. 

From September 27 to October 2 A3 will be very low on the horizon just before sunrise.  You should be able to see it with binoculars or a telescope if you have a clear horizon and a very dark sky.  After this it’s too close to the Sun for us to see.  October will be the best month for seeing A3 in the evening sky.  October 12 ^th is the comet’s closest approach to Earth so it will be at its brightest and it will be well placed above the western horizon for viewing, however the Sun will still be up.  It may be naked eye at this time, but for sure visible in binoculars or a small telescope but be extremely careful if using these instruments not to look directly at the sun.  This comet is moving fast, by October 14 ^th it will be above the horizon after sunset and will appear higher in the sky each following night.  Predictions are it will be a naked eye comet.  As A3 races away from Earth it will quickly fade in brightness.  By the end of October a telescope will be needed to see A3.   

Comets are HARD to predict and more often than not don’t live up to predictions.  There has been much written about A3 since its discovery, will it survive its trip around the Sun, will it be a brilliant naked eye comet with an incredible tail or will it be a dud. We’re about to find out.