AstroCal – October 2024
Comets do not always behave as advertised. Sometimes they are not as spectacular as predicted and sometimes they perform beyond what is expected. I will let our friends at Sky Calendar cover what may happen on the cometary front this month: “There’s a chance that Comet C/2023 A3 may surge in brightness around October 9 as it passes nearly between Earth and Sun. It’s then moving rapidly eastward, and within a few days it emerges into the western evening sky. The Comet’s motion slows from more than 5 degrees daily to only 1.5 degrees while its brightness is expected to fade by a factor of 10, or 2.5 magnitudes. For details on the comet, the bright evening planets Venus and Saturn and fainter Uranus and Neptune, check our Sky Calendar Extra Content page at abramsplanetarium.org/msta/”. If one wishes to try and locate Comet C/2023 A3, it will be low in the western sky in Virgo – the Virgin on October 13 and move by small increments through Ophiuchus toward the bright star Altair in the constellation Aquila, the Eagle near the end of the month.
With a New Moon taking place on October 2, the first view of the Young Crescent Moon will appear low in the WSW on October 6 with bright Venus a bit to the right very near the horizon. Lunar apogee will also occur on Oct 2 and at 252,597 miles, it will be the most distant of the year. Other Lunar events will include the First Quarter Moon (Oct 10), Lunar perigee at 221,937 miles (Oct 16), Full (Supermoon) Moon (Oct 17), Last Quarter Moon (Oct 24), and a second lunar apogee on Oct 29 (now only 252,276 miles from Earth). Halloween lovers will have to endure another spooky holiday without a Full Moon, but then again, darker skies will make for better viewing and an even spookier Halloween.
Jupiter, shining at mag -2.5 in Taurus, the Bull, remains the brightest of the predawn ‘stars’. This gas giant’s motion across the starfield will appear to stop on October 9 just short of the tips of the Bull’s horns. Jupiter will then go into retrograde motion until early February of 2025. During retrograde motion, a planet will appear to be moving backwards across the sky from the normal motion and in this time, Jupiter will move about 10 degrees before stopping again just short of the Bull’s eye, the star Aldebaran.
Next door to Taurus, in the constellation of Gemini, the Twins, Mars will brighten from +0.5 to +0.1 as it approaches opposition in January of 2025. On October 19, Mars will pass just 5.7 degrees south of one of the Twin star, Pollux. This will be the first of three conjunctions Mars will have with Pollux the other two coming on Jan 22 and Mar 30, 2025.
Venus begins October as the ‘star’ of the western sky at mag -4.6 (the lower the number, the brighter the object. The faintest star one can see has a magnitude of +7.2). It will be low to the horizon in the constellation of Libra, the Scales. As it moves through Scorpius, the Scorpion near the end of the month, it will be higher above the horizon. Look for Venus to pass close to and above the reddish star, Antares, the Eye of the Scorpion. Antares is also known as the Rival of Mars because when the two are near each other, both have similar coloring. The difference can be seen in that Antares, like all stars, will appear to twinkle due to atmospheric interference whereas planets, being much closer to Earth, will not twinkle.
One of my favorite stars,Capella, can be easily observed in the NE during the fall and winter months. When I first began teaching in Ontonagon, I discovered a six inch Newtonian reflecting telescope in the science department store room. It was a little worse for wear but it was the exact model that we had used for some view sessions for the two astronomy classes I had taken at Northern Michigan University. After getting the mirrors and sighting scope aligned, I told my students that I would set it up for some evening observation sessions. I parked on Airport Road near the golf course on a couple of evenings and invited anyone who would like to drop by to come and see what was out there.
Jupiter just happened to be prominent in the eastern sky in the fall of 1975 so that was our first object of interest. Someone pointed out Capella to the northeast so we focused on that next. It made a good way to illustrate how stars will twinkle where planets do not. Capella, is located in the constellation Auriga, the Charioteer. It is an interesting object because it not only appears bright (it is the sixth brightest star in the sky), but it also seems to change color from blue to green and occasionally red. Perhaps this is caused because Capella is not a single star. It is a grouping of two binary stars that orbit each other. Two of these binaries are giant yellow stars and the other pair is made up of smaller, red stars. Even without a telescope, it is a spectacular site that is visible all night. Capella is a circumpolar constellation for anyone located north of 44 degrees N latitude meaning the Earth’s rotation makes it appear to rotate around Polaris, the Pole Star.
Compiled by Ken Raisanen of WOAS-FM – information provided by Abrams Planetarium Sky Calendar, Michigan State University. More information and subscription information can be found on their website at http://abramsplanetarium.org/skycalendar/ or on X (formerly Twitter) at http://twitter.com/AbramsSkyNotes. Yearly subscriptions cost $12 and can be started anytime.
Top Piece Video – We mentioned Taurus enough to include the song of the same name by Spirit – sorry, could not find a live version!