Skywatch Line for Friday, October 2, through Sunday, October 4

This is Dudley Observatory’s Skywatch Line for Friday, October 2, through Sunday, October 4, written by Alan French.

The Moon reaches last quarter on Sunday afternoon, so a waning gibbous Moon rises late in the evening on Friday and Saturday, and it will be a waning crescent when it rises Sunday night. The Moon rises at 10:10 pm Friday, 11:02 pm Saturday, and 11:57 pm Sunday.

In the early evening the Milky Way, that hazy band that is the combined light of many distant stars in the plane of our galaxy, stretches high across the sky. It may be invisible to people in or near the city, where the lights brighten the sky, but it is a lovely sight from the dark skies away from town. Around 8 pm it stretches roughly from the south southwest to the north northeast. It is brightest and broadest in the south, a beautiful sight as it passes overhead through Cygnus, the Swan, and its luster diminishes as it reaches the distinctive “W” star pattern of Cassiopeia, the Queen, high toward the northeast.

Dark skies are not the only requirement for your best views of the Milky Way – your eyes should also be thoroughly adapted to the dark. You’ve certainly noticed that your eyes gradually get used to the dark, allowing you to see better with time. There are two changes. The pupil opens wider within seconds, allowing more light into the eye. There is also a chemical change which greatly increases your eye’s sensitivity. The full transformation takes 30 to 40 minutes.

White light ruins your dark adaptation and the process has to start again. To preserve their night vision amateur astronomers use dim red lights, which allow reading star charts and notes without ruining one’s night vision. Red plastic or construction paper can easily turn a regular flashlight into an astronomer’s flashlight – but remember it should be just bright enough to read charts when you are completely used to the dark.

A reclining lawn chair is ideal for exploring the Milky Way, and there is even more to see with binoculars.

We often recommend observing the Moon with binoculars or a telescope when it is near first quarter. It is a similarly great target near last quarter – but the timing is not convenient for most people. If you’re an early riser the Moon, just past last quarter, will be high in the southern sky at 6:00 am Monday morning. When the Moon is high in the sky the views tend to be steadier and detail better seen. Monday morning the sunset line or terminator is near the center of the Moon’s disk, ideally placed for viewing. Along the terminator shadows are long and details stands out in bold relief.

If you took advantage of National Observe the Moon Night last Saturday, just before first quarter, you probably noticed the Moon was not very high in the sky then.

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