# Tagged Questions

1answer
181 views

### Calculate sunrise, where does the magic numbers come from?

In this question about how to calculate sunrise, there is a link to a page that describes a algorithm to calculate sunrise sunset. But when I start to follow the instructions I find that there is a ...
1answer
71 views

### Does the sun's bearing at a given time vary, and if so, how?

More an astronomy question, but Physics is the closest stack exchange category I could find and Google doesn't have the answer. Granted, the sun's elevation changes for a given time of day throughout ...
1answer
191 views

### Calculating the length of day at any time of the year? [duplicate]

Is it possible to calculate the length of the day at various location (distances) from the sun? I hear agricultural scientists are able to do that. To make calculations easier assume there is no axis ...
0answers
34 views

### What is the formula for calculating the length of any given day (sunrise to sunset)? [duplicate]

In a specific date what law gives us perfect measurements and how will we measure if latitude is given?
1answer
937 views

### Finding radius of Earth through observation of Sun's motion

The question I'm about to pose is from a physics book I had recently bought. Since I am very interested in physics I am quite keen in understanding how this question can be solved. Before I present ...
1answer
1k views

### What is actually meant by 'sun set' and 'sun rise' times, when taking into account the mirage due to light bending in the atmosphere

I’ve heard from the likes of Brian Cox that what we see of the sun during a sunset and sun rise is actually the mirage of the sun. The Sun has actually set/risen and we see it due to the way light is ...
2answers
372 views

### How to calculate the amount of night time during a flight?

I have been asked to find a way to calculate the amount of time that a flight takes during night time. So far, I have the departure latitude and longitude and the time of takeoff, the arrival ...
1answer
1k views

### How to determine day/night based on latitude, longitude and a date/time?

Is there a simple method of determining, given a UTC date/time, whether it is day or night at a given lat/long coordinate? I am currently using a formula based on a Sunrise/Sunset Algorithm from the ...
1answer
150 views

### Why isn't sunset time in sync with solstice?

The winter solstice in the Northern Hemisphere in 2011 is on December 22. But if I look at the sunset times for a location such as Washington, DC on the USNO site, the sunset time starts reversing ...
1answer
673 views

### How to calculate how many degrees the Sun is from the horizon?

Given a position on earth (latitude/longitude, and maybe also height relative to sea-level) and a time, what's the algorithm to find how many degrees the Sun is from the horizon? And the same for ...
3answers
5k views

### How fast will the sun become a red giant?

I've read many accounts of our sun's distant fate, but what I've never heard is on what time scale these events occur. For instance, when the sun runs out of hydrogen, I presume it doesn't just WHAM! ...
2answers
185 views

### How to create unusual sundial?

I am considering small "artsy" project. I would like to create sundial by placing gnomon on the window and painting hour lines on the window facing wall. Since this is to be placed in bedroom I am ...