by Geoff Chester, USNO Public Affairs | 10 October 2023 Jupiter with its moon Callisto, 2023 October 4, 03:01 UT imaged from Alexandria, Virginia with a 23.5-cm (9.25-inch) telescope The Moon begins the week as a waning crescent in the pre-dawn sky and ends it as a waxing crescent in the evening. New Moon occurs on the 14th at 1:55 pm Eastern Daylight Time. Look for Venus about 10 degrees above the Moon before dawn on the 11th. On the evening of the 17th look for Luna to the west of the ruddy star Antares low in the southwest about an hour after sunset. The New Moon that occurs on the 14th is a special one. Residents along a path that stretches from the coast of Oregon, through the Four Corners region, New Mexico, and south Texas will be treated to a “ring of fire”, or annular, solar eclipse. These eclipses occur when the tip of the Moon’s umbral shadow doesn’t reach the Earth’s surface. Along the central eclipse path, observers will see the dark disc of the Moon advance across the face of the Sun until it is surrounded by a bright ring of the Sun’s photosphere. Unlike a total solar eclipse. The Sun’s corona is not visible, and proper eye shielding must be worn throughout the entire event to prevent permanent eye damage. The partial phases will be visible from the entire “lower 48” United States, with the greatest obscuration visible over the western states. Here in the Washington area, the partial eclipse begins at noon EDT on the 14th. Maximum eclipse will occur at 1:19 pm, and the eclipse will end at 2:39 pm. At mid-eclipse about 30 percent of the Sun will be obscured by the Moon. You can compute the local circumstances of the eclipse for any location in the U.S. by using our eclipse information page. This eclipse serves as a warm up to the next “Great American Eclipse” that will occur on April 8th next year. That event will be a total eclipse that will span much of the nation from Texas, through the central Mississippi valley, to northern New York and New England. If you miss that one, the next total solar eclipse that will be widely visible in the U.S. won’t occur until August 12, 2045! The October observing campaign for the citizen-science Globe at Night continues through the evening of the 14th. This month’s target constellation, Cygnus, the Swan, is high overhead at the end of evening twilight. By 10:00 pm, Cygnus and the other constellations whose brightest stars form the Summer Triangle asterism are heeling toward the west, while the Great Square of Pegasus climbs higher in the east. You may notice that the southern half of the sky is notable for its lack of bright stars, with one notable exception. The brightest object in this part of the sky is the planet Saturn, but if you look southeast of the planet you will find the lonely star Fomalhaut. Located about 25 light-years from Earth, this was the first star to reveal a large disc of circumstellar dust that may be indicative of a forming planetary system. By midnight, the next seasonal geometrical figure is climbing over the eastern horizon. Looking due east at this time you should see about half of the Great Winter Circle, with the central figure of Orion seemingly striding into the sky. Several of the circle’s bright stars are already in view, including Aldebaran in Taurus, the Bull, and Capella, the brightest star in Auriga, the Charioteer. Between the yellow glimmer of Capella and the bright glow of the planet Jupiter you should be able to glimpse some of the stars of the Pleiades star cluster, one of the most storied groups of stars in the sky. My first glimpse of the Seven Sisters in the evening sky remind me that winter is just around the corner, and the cluster has long been a portent of harsh weather for sailors in the Northern Hemisphere for centuries. Saturn crosses the meridian at around 10:00 pm local time, giving skywatchers ample time to look at him through the telescope. There is something magical about seeing this cold, distant world floating in the eyepiece, surrounded by the tiny sparkles of his brighter icy moons. The rings themselves are one of the most amazing wonders of nature. They consist of billions of icy bodies that form an enormous, flat disc. Spanning a diameter of some 240,000 kilometers (150,000 miles), they are only 20 meters (66 feet) thick! Jupiter is approaching opposition, which will occur in just over three weeks. By 10:00 pm he already dominates the eastern sky, beckoning for a telescopic view. I had a very nice session observing the giant planet last week, and I always marvel at his constantly changing cloud patterns as the nights (and even hours) pass by. Venus greeted me this morning in the company of the waning Moon, and in the pre-dawn sky you will be hard-pressed to miss her. The dazzling planet is close to her greatest elongation from the Sun and at her peak brightness. This is the perfect combination of events for people who live in very dark locales to look for their shadow cast by the planet before the onset of morning twilight.