Twilight Zone

At dawn, civil twilight begins when the sun is 6 deg below horizon and ends at sunrise.
At dusk, civil twilight begins at sunset, and ends when the sun is 6 deg below the horizon.

At dawn, nautical twilight begins when the sun is 12 deg below horizon & ends when civil twilight starts.
At dusk, nautical twilight begins when civil twilight ends, and ends when the sun is 12 deg below the horizon.

At dawn, astronomical twilight begins when the sun is 18 deg below horizon & ends when nautical twilight starts.
At dusk, astronomical twilight begins when nautical twilight ends, and ends when the sun is 18 deg below the horizon.

Golden hour is when sun is between horizon and 6 degrees above horizon.

At dawn, blue hour starts when the sun is 4 degrees below horizon.
At dusk, blue hour starts when the sun is 8 degrees below horizon.

Golden hour is short time interval after sunrise and before sunset.

Blue hour is short time interval before sunrise and after sunset.


Astronomical (18-12 deg), Nautical (12-6 deg), Civil (6-0 deg), Golden Hour(0-6 deg)

Night, Astronomical, Nautical, Civil ->Blue Hour, Sunrise, Golden Hour. Day

Day. Golden Hour, Sunset, Blue Hour->Civil, Nautical, Astronomical, Night