Skywatch Line for Wednesday and Thursday, October 30 and 31, 2024, written by Alan French

This is Dudley Observatory’s Skywatch Line for Wednesday and Thursday, October 30 and 31, 2024, written by Alan French.

The Sun rises at 7:28 A.M. on Wednesday and sets at 5:50 P.M. On Thursday it rises at 7:29 and sets at 5:48. This Thursday has 18 and a half minutes less daylight than last Thursday. In October we lose 1 hour, 16 minutes of daylight.

The Moon reached last quarter early last Thursday and is now headed toward new, which it will reach this coming Friday morning. Early risers, at least on Wednesday, will get to enjoy a waning crescent, old Moon in the eastern sky before sunrise. On Wednesday morning the Moon rises at 5:34 A.M. At 6:30 look for a 3.7% sunlit, thin crescent Moon, 9 degrees above the east southeastern horizon.

Thursday morning the Moon does not rise until 6:36 A.M., only 53 minutes before sunrise. Spotting it will require an excellent view to the east southeast and exceptionally clear skies. At 6:45 the Moon will be just 1 degree above the east southeastern horizon and only 1% of its visible face will be in sunlight. Such a slim crescent will be a difficult target under the best of circumstances. The star Spica will be 3 ½ degrees above and slightly south (right) of the Moon. By 7:00 the Moon will be 3 degrees above the horizon, but morning twilight will be a bigger hindrance to spotting it.

Venus is low in our skies an hour after sunset. Look toward the southwest around 6:50 P.M. when Venus, shining at magnitude -4.0, will be just under 7 degrees above the horizon.

Saturn now rises just before 4:00 P.M. and is 36 degrees above the south southeastern horizon by 8:00 P.M. It transits at 9:17 when it will be at its highest, 38 ½ degrees above the southern horizon. Saturn’s largest and brightest moon, Titan, shines at magnitude 9.0 and can be easily seen in any telescope, appearing like a star in-line with Saturn’s rings. Around 9:00 Wednesday evening Titan will be just over one ring-diameter to the planet’s east. On Thursday it will be a little farther from Saturn.

While Jupiter has four large moons bright enough to spot in any astronomical or spotting scope, and no others visible easily in most amateur telescopes, Saturn reveals more moons as aperture increases. Rhea is easy, visible in telescopes of less than 5 inches aperture, followed by Dione and Tethys, visible in telescope of 6 inches aperture and larger. Many planetarium apps will show the changing positions of Saturn’s moons. (Keep in mind that limitations on what can be seen in a particular aperture telescope are only rough guidelines. They depend on visual acuity, experience, seeing and transparency, and the optical quality of a telescope.)

Some of you were able to see Comet Tsuchinshan-ATLAS earlier this month. You may also have heard about Comet ATLAS (C/2024 S1), which might have been visible next month. Unfortunately, images from the coronagraphs on the Solar and Heliospheric Observatory (SOHO) show the comet evaporated as it passed within 0.008 Astronomical Units (1.2 million KM/740,000 Miles) of the Sun as it reached perihelion.

Comet ATLAS was a Kreutz sungrazer, comets that are remnants of a large comet that broke up about 1,000 years ago. SOHO has discovered thousands of them, and most have evaporated as they passed close to the Sun. An early brightening of Comet ATLAS had astronomers hoping it was one of the larger fragments and might survive its close approach to the Sun.