by Geoff Chester, USNO Public Affairs | 15 October 2024 Comet C/2023 A3 (Tsuchinshan-ATLAS), imaged 2024 October 14, 23:51 UT from Alexandria, Virginia with a Canon EOS Rebel SL2 DSLR. HDR stack of three 8-second exposures, processed with easyHDR and Topaz Photo AI The Moon brightens the evening sky this week, waxing to her full phase, which falls on the 17th at 7:26 am Eastern Daylight Time. October’s Full Moon is widely known as the Hunter’s Moon. It has similar geometry to September’s Harvest Moon, and here in Washington the interval between successive moonrises around Full Moon is just half an hour. In the Northern Hemisphere, this gave hunters a bit of extra light to pursue game across the stubble of the harvested fields. Native Americans also called it the Falling Leaves Moon and the Freezing Moon. Luna moves from the relatively star-poor autumnal constellations into the rising stars of winter by the week’s end. Look for the Pleiades star cluster to the west of the waning gibbous Moon on the evening of the 19th. On the following night you will find her about five degrees above bright Jupiter. As I mentioned last week, a comet is gracing the western sky this week during the early evening hours. Comet C/2023 A3 (Tsuchinshan-ATLAS) passed between the Earth and the Sun on October 9th, moving into the evening sky. It has been putting on quite a show for folks with dark skies, but it is also visible to urban dwellers who know where to look. I was able to spot it at around 7:45 pm EDT on the 14th from an open space near my home in Alexandria, Virginia. It was faintly visible to the naked eye despite high clouds and light from the waxing Moon and local streetlights, but my best view was through a pair of binoculars, where its glowing coma and bright tail were easy to see. It will gradually climb higher over the next several evenings as it moves eastward against the background stars. On the evening of the 15th it will pass one degree south of the globular star cluster Messier 5, which should provide an interesting view in binoculars and small telescopes. Unfortunately, as it climbs higher in the western sky, it will begin to fade, but it should remain a binocular target for city and suburban dwellers through the rest of October. Catch it while you can! And now a personal note to all of my readers. On November 1st I will retire from my position as the Public Affairs Officer for the U.S. Naval Observatory. After 27 years at this wonderful place and 19 years at the Smithsonian’s Einstein Planetarium, it is time for me to move on to enjoy more personal pursuits. I began writing “The Sky This Week” back in 1986, first as a script for a weekly telephone update line for the Smithsonian Institution providing updates on Halley’s Comet, then as a weekly blog post for the Smithsonian’s website. When I assumed my position at the USNO in 1997 I brought the blog with me, and for the most part have provided weekly installments since that time. I would like to thank all of my long-time readers for the continued support you have shown over the years. I honestly have no idea of how many of you are “out there”, but it has been a pleasure to try to provide a practical guide for celestial events, sky lore, and even some astrophysics to you. I have been actively engaged in enjoying the night sky, both as a professional but mostly as an amateur, for well over fifty years. I leave my post with the knowledge that my successor is the right person for the job and the Observatory. She comes to the position with a degree in astronomy and experience running outreach programs for national parks and the Mauna Kea Observatory. She is also adept at social media, a skill I have never really mastered. I will continue to be active in the local Washington, DC amateur astronomy community. If you attend the monthly stargazing programs at Sky Meadows State Park or the Smithsonian’s Udvar-Hazy Center I’ll likely be there. I will also devote more of my time to advocating for dark skies, promoting participation in the Globe at Night monthly observing campaigns and working on behalf of DarkSky International. May all of you have clear nights, dark skies, bright stars, and the wonder that the night sky brings to us. I have often said that the night sky is the world’s largest national park, and it is free for anyone who spends a little time looking up. Sincerely, Geoff Chester