Skywatch Line for Wednesday and Thursday, October 11 and 12, 2023

This is Dudley Observatory’s Skywatch Line for Wednesday and Thursday, October 11 and 12 written by Alan French.

The Sun rises at 7:04 A.M. on Wednesday and sets at 6:20 P.M. On Thursday it rises at 7:05 and sets at 6:18. This Thursday has just under 20 minutes less daylight than last Thursday.

The Moon was at last quarter this past Friday and is headed for new. New Moon occurs early Saturday afternoon and parts of the United States, stretching from Oregon to Texas, will see an annular solar eclipse. With the Moon near apogee, its farthest point from Earth, it will appear slightly too small to cover the entire Sun. At maximum eclipse there will still be a ring, or annulus, of sunlight around the Moon.

The rest of the United States, outside the path of annularity, will see a partial solar eclipse. From here it will begin at 10:10 A.M. on Saturday, October 14, and end at 2:30 P.M. Maximum eclipse will be at 1:20 P.M. when just over 20% of the Sun will be obscured by the Moon.

As with any solar eclipse or solar viewing, it is important to view the Sun safely to protect your vision – improper solar viewing can cause permanent vision loss. For details on safe viewing, see How to View a
Solar Eclipse Safely | Solar Eclipse Across America (aas.org). Solar eclipse glasses or a shade 14 welder’s filter plate, which you may have from a previous solar eclipse, are safe.

If you are up at 6:00 A.M. Thursday morning look toward the east. Brilliant Venus will be 30 degrees above the horizon and a slender crescent Moon, just 5% in sunlight, will be 12 degrees high. Look for Earthshine, the faintly visible, larger part of the Moon not in direct sunlight but illuminated by the light of the nearly full Earth in the Moon’s sky. By 6:30 the Moon will be 17 degrees high.

Friday morning provides a chance to see a very slender, old Moon. At 6:00 A.M. the Moon will be a mere 1 degree above the eastern horizon, so you will need an excellent view to the east, unobstructed by trees or buildings and free of clouds and haze. The Moon will only be 1 ½% in sunlight and will be a very thin crescent. By 6:15 it will be 3 ½ degree high and by 6:30 six degrees up, but morning twilight will provide more interference.