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Coffee_Huffer t1_iy5sqhq wrote

I would say when the sun is completely on the other side of the Earth to the observer. Take note of what time of day the Sun is right in the middle of the sky. Then that time at night the sun would be on the opposite side of you.

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Coffee_Huffer t1_iy5xqk8 wrote

Replying to El_Topo_54 (#748,035)

I haven't gone as far as measuring it, but for me it's seems closer to one. Different time zones, being on the edge of a time zone, different time changes you may be observing such as daylight savings time can all vary your results.

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Ok_Neighborhood_1203 t1_iy5zyto wrote

I still have a lot to learn, but I like to go out right at sunset and get my telescope set up. Start getting the computerized mount set up and aligned to the first two stars I see while there is still enough daylight not to trip over it. It also gives the optics a chance to acclimate to the weather. Then I use the time waiting for it to get truly dark to pick my target and fine tune the alignment with 30 second single exposures (if I can see the target at all). I'm on a budget system though (alt-az computerized mount with webcam-style eyepiece camera and laptop). If you have a more permanent setup, a more capable mount, or otherwise faster setup, you may not need as much prep time as me.

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beef-o-lipso t1_iy64ax2 wrote

Look up twilight definitions and you get something like this https://www.weather.gov/lmk/twilight-types#:~:text=Astronomical%20Twilight%3A,urban%20or%20suburban%20light%20pollution.

The afternoon events come earlier as we approach the winter solstice and later as we approach the summer solstice. Generally speaking, you can start alignments during civil twilight or sooner. If you can see a star, you're good to go.

Viewing DSOs can start usually around nautical twilight when it's gets dark. Then Astronomical twilight is the period where the sky is darkest.

If you go to this site https://www.timeanddate.com/sun/ and enter your location, it will give you the time frames for solar events.

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