Questions tagged [twilight]
The twilight tag has no usage guidance.
8
questions
1
vote
0answers
19 views
What magnitude stars are visible during a quarter moon, during nautical twilight?
Assuming I'm looking for stars at least 50° from the quarter moon, is there any way to determine what magnitude stars would be visible to the naked eye, in a sky without light pollution, during ...
0
votes
0answers
31 views
What is the formula to input date, time and longitude. Where I can get latitude of the civil twilight back?
I am making a watch app, where I need to know where there is currently sun, and where it's not.
I need to have some sort of formula/function to insert: date, time and longitude, and get back the ...
0
votes
1answer
60 views
Is the appearance of the twilight not constant in the interval before the sunrise?
I've been told by an astronomer in past, that the appearance of the twilight isn't constant in the interval before the sunrise. That is to say that not every day the earth is going at the same speed, ...
2
votes
2answers
129 views
Is astronomical twilight always seen when the sun is 18 degrees under the horizon?
Is astronomical twilight always seen when the sun is 18 degrees under the horizon or are there other factors that may influence it?
3
votes
1answer
238 views
Significance of astronomical twilight
What is the significance of astronomical twilight? Astronomical twilight is when "the geometric center of the Sun's disk is between 12 and 18 degrees below the horizon" , but what, if any, ...
2
votes
1answer
71 views
what degree in the sky does the sun change color?
I would like to know at what angle in the sky the sun changes from a white yellow to orange and red. I know that after sunset it's considered twilight until 18° beneath the horizon. So how many ...
0
votes
0answers
61 views
How does the Astronomical Twilight depend on the night length or the day length?
Some references say that the Astronomical Twilight starts at the last 1/8th of the night length, so it is long in Winter and short in Summer;
But by using the 18 angle (sun elevation below the ...
14
votes
1answer
539 views
At Mars' equator how long does twilight last?
With Mars' thinner atmosphere I'm assuming twilight would not last as long compared to the duration on Earth. Has there been any determination of the length of twilight on Mars at the equator or any ...