October will be an interesting month in the sky. Venus will continue to be brilliant and unmistakable as it slowly climbs out of the twilight glow. Also, if you have sharp eyes and a clear western horizon, for a short time at midmonth Mercury might be glimpsed to the lower right of Venus very low in the sky.

While out in the early evening to observe Venus and maybe Mercury, you might also want to try and see Comet C/2023 A3 (Tsuchinshan – ATLAS) that may or may not be visible. Comets are not very predictable. Start looking about 45 minutes after sunset on October 15 to the left of Arcturus, the bright star that can be found by extending the curve of the Big Dipper’s handle. From there the comet will dim as it moves southward and higher in the sky. It will be to the upper right of Venus on October 20 and above Venus on October 20. Binoculars will help in finding it.

After it is dark, Saturn will dominate the southern evening sky. It will be in the very dim constellation Aquarius (the Waterbearer) to the lower left of the “water jug.” This only easily recognizable feature of Aquarius is a small “Y” shaped grouping of four stars that can be seen in a dark sky or with binoculars. Saturn will be followed into the sky by very bright Jupiter that will rise at about 11:00 in early October and at about 9:00 at the end of the month. It will be just to the left of the horizontal “V” shaped face of Taurus (the Bull) and between its horns. It will also be above the easily recognized Orion (the Hunter). Jupiter will be followed about two hours later by Mars that will be passing through Gemini (the Twins).

Turning your attention to the northern sky, look high in the northeast for Cassiopeia (the Queen). During October, her five brightest stars will form the shape of a “3” that will rotate to an “M” as she moves higher in the sky. Cassiopeia is very helpful in locating other stars and constellations of the northern sky. Firstly, the open part of the 3 or M points generally in the direction of Polaris, the North Star, the brightest star in that part of the sky. This is especially useful in autumn when the Big Dipper, which is normally used to find Polaris, is very low in the sky.

If the five stars of Cassiopeia are numbered with 1 being the star on the upper or western end, they can be used to find other constellations. A line from star 2 through star 1 points to the dimmer, 5-stared Cepheus (the King). He is shaped like the stick figure of a house with its pointed roof near the North Star. A line from star 3 through star 4 will point to Perseus (the Hero), and a line from star 3 through star 2 will point to the “square” of Pegasus (the Winged Horse). This main part of Pegasus is an almost perfect square about the size of your fist at arm’s length, and it is tilted so it seems to be standing on one corner. The square represents the front half of the upside-down horse, and the stick-figured neck and face of the horse extends out from the star on the right. Extending out from the corner on the left is a curved line of three stars that are the main stars of Andromeda (the Princes). Finally, a line from star 3 through 1 points to Deneb, the tail of Cygnus (the Swan), part of the summer triangle.

Observing Highlights

Oct. 5: The crescent Moon will be close to the left of brilliant Venus low in the west during evening twilight.

Oct. 7: The Moon will close to the left of Antares, the bright reddish heart of Scorpius (the Scorpion).

Oct. 12 : Star Party sponsored by Grout Museum & Black Hawk Astronomy Club, Prairie Grove Park, Waterloo, 9-10:30 p.m.

Oct. 13 : The Moon will be to the right of Saturn. It will move in its orbit and be closer to the lower left of Saturn on the 14th.

Oct. 19 : The Moon will be above Aldebaran, the bright eye of Taurus (the Bull), and to the upper right of Jupiter.

Oct. 23 : After they rise just after midnight, the Moon will be above Mars and to the right of Castor and Pollux, the bright twin stars of Gemini (the Twins). On the morning of the 24th, the Moon will be to the lower left of Mars and farther to the lower left of the twin stars.

Oct. 25 : Venus will pass just above Antares in Scorpius (the Scorpion) low in the southwestern sky. They will be almost as close on the evening of the 25th. Start looking about 30 minutes after sunset.