I have seldom brought passing comets to sky-watchers’ attention through my column. Not because they are rare, but because most comets remain too dim to be seen easily except through binoculars or small telescopes.
However, mid-October brings a highly anticipated comet into view with its closest approach to Earth on Oct. 12.
The comet’s name is Comet Tsuchinshan-ATLAS, officially known as Comet C/2023 A3.
Comets’ odd names derive from the person who first spotted them — usually an amateur astronomer — and a numerical code for when they were found.
Meanwhile, Venus dominates the evening western sky all month in the 45 to 75 minutes after sunset.
On Oct. 5, a thin crescent moon will be seen just below Venus.
We will start our search for Comet Tsuchinshan-ATLAS on Oct. 13-14 when its orbital path into the inner solar system takes it just above and right of Venus.
Venus’ brightness acts as a great guide to start the search as the comet will move from right to left away from Venus and across the southern sky over the next week.
Use binoculars to look for it, though it is possible that by that time the comet will be bright enough to be visible without aid.
Only time will tell since comets hardly ever follow brightness estimates.
Once the comet is spotted, follow it from night to night across the southern sky for the next two weeks, especially from Oct. 14 to Oct. 19 when its tail develops.
Moonlight may dim the sky some so continue to use binoculars to see the tail.
After Oct. 20, the comet will fade as it moves away from us, but take every opportunity to look for it because it could be the brightest comet in some years.
Saturn is well up in the southeastern sky as soon as darkness falls, and is a great telescopic object all month where its rings come into view. It is visible all night until early morning.
Jupiter rises about 10 p.m. in the eastern sky with its best views from midnight to dawn.
The waning gibbous moon will be near the giant planet on Oct. 20-21.
Mars can be seen in the eastern morning sky and getting brighter all month while moving out of Gemini and into Cancer, the two zodiac constellations that currently form its background in the sky.
A slim crescent moon will be near Mars on Oct. 1.
Finally, the Orionid meteor shower peaks on Oct. 21, but the bright gibbous moon may make it difficult to spot the meteors. Look southwest however, one hour before sunrise, when 15 to 20 meteors per hour may be seen around the familiar constellation Orion (the hunter).
The full moon is Oct. 17.