When, in relation for example to sunset, does "night" or nighttime actually officially begin?

Question

I am looking for from when sunset begins to the actual onset of "night", when for example would I be able to fully see 3 to 5 stars?

Answer 1

Check out the definitions of civil, nautical, and astronomical twilight: http://en.wikipedia.org/wiki/Twilight

Answer 2

It depends on what you want to call "night". We can determine the moment when the sun makes contact, crosses, and leaves the horizon, and we can allow for the average amount of time it takes for the sky to darken to a specific level, dust, clouds and artificial light not withstanding. But the level that will satisfy your needs is subjective.

Drive-in movie theaters would always show the cartoon about a half hour after sunset, letting the sky grow darker for the main feature. On Independence Day, we light off the smoke bombs and parachute rockets at sunset as we wait for the main event. But "night" is a function of the observer's needs.

The three stars rule is iffy. Are we talking 0-magnitude stars? Which ones are in the sky tonight? Are there clouds? Where did all these porch lights come from? Check out the astronomical definitions in the other post. For your own purposes, you might want to spend an evening observing how long after sunset the sky gets dark enough for you.

Answer 3

I have a fuzzy memory of some map which was showing the edge of night as being maybe 30 minutes after sunset. It might have been a map of satellite orbits or something like that. My point is I believe there is an official designation for the length of dusk, which you could dig a little and find out.

Answer 4

It is more based on how far you can see then anything else. If you can see 1000 feet then it is day time if you can't it is night time.. I tried to look up what is the legal visibility but did not have any luck..