# Questions tagged [sunset]

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### Day timings equations

Is there a reference or equations to calculate timings such as (sunrise, golden hour, noon, sunset) with high accuracy at UTC?
52 views

When or at what altitude does the sun completely disappear from view? When does the effect of the sun on objects facing it begin, for example, the formation of shadows when sunlight hits objects? ...
1 vote
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### What would sunsets look like around different star types?

I have always wondered what a sunset would look like around different types of stars. I have tried to do some research into the types of light refraction, but I cannot find any answers anywhere, and ...
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### What is the distance between sunrise and sunset along a parallel of latitude for declination other than 0?

I would like to calculate the distance between sunrise and sunset along a parallel of latitude, e.g., 45 degrees north. What I've done is: Earth's circumference at the equator is 40075 km. Earth's ...
• 204
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### Geometric effect on sun's position in the sky at the equator

This question is about an explanation of "Sunrise and Sunset Times Near the Solstices" on the official website of the US Naval Observatory. It is mentioned in the explanation article that, ...
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### How can the new moon set before the sun, as will happen in some locales on November 13, 2023?

I have somewhat of an interest in sighting the new moon. I recently heard a lecture by someone who had written a program to provide the conditions for the first new moon sighting for any location for ...
325 views

### Sidereal time of rising and setting of the sun on the arctic circle

$$cos(h)= -tan(\delta)tan(\phi)$$ $$\Theta = h + \alpha$$ if these two equations are the correct equations to solve the following question why doesnt it yield the same answer for the sideral ...
• 125
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### Where can I download the historic sunrise and sunset times for a location?

As the question indicates, I would like to know the sunrise and sunset times of a location. This is to evaluate the impact of day and night variations of a time series. Is there a way to download this ...
1k views

### Why is moonrise/moonset before sunrise/sunset on some days but after on others?

While looking at the daily forcasts for the week on The Weather Channel app on my phone I noticed that today, Thursday the 18th, both moonrise and moonset are roughly half an hour to an hour BEFORE ...
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### Display the lines of solar altitude on the map

Following this question: Calculate lines of equal solar altitude I would like to have the possibility of displaying the lines of equal solar altitude on the map as per the image below: including also ...
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### math tool to compute time of sunrise and sunset

What is the mathematical tool that enable to compute time of sunrise and time of sunset at a specific geographical location in the same part of a year, say given month and day exactly? I have noticed ...
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### How to roughly calculate sunrise and sunset with a spreadsheet application

I am looking for a way to roughly calculate sunrise and sunset for a given lon/lat in mid Europe for each day of a year using a spreadsheet application. The thing doesn’t need to be very precise, but ...
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1 vote
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### Meaning of $\cos H$ in the rising and setting formula

In the rising and setting formula$$\cos H=-\frac{\left(\sin\nu+\sin\phi\sin\delta\right)}{\cos\phi\cos\delta},$$ $H$ is hour angle, $\nu$ is vertical shift, $\delta$ is declination and $\phi$ is the ...
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### How to find the first Julian day with the same Earth-Sun constellation

There are quite some sources for astronomical calculation formulas, e.g. Astronomy Answers: Position of the Sun, which is e.g. used by KDE's Night Color plugin to calculate the time of a sunset or ...
1 vote
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### Why do sunrise/sunset times (for a given location) vary based on the source of the data?

I've noticed that different reputable weather websites will give different times for sunrise/sunset for the exact same location. I've seen variation by 25 minutes or more, for sunset on the same date ...
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### Why isn't Spring equinox on 1st of April?

AFAIK the summer and and winter solstices are based on longest day and longest night doesn't fall on 1st of Jan and July 1st because we consider the day to begin and end when the middle of the sun is ...
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### How can I calculate my position (lat/lon) given a sequence of solar-elevation measurements at known times?

The "forward" problem (given time and lat/lon, find solar position angles) is well documented, e.g. here. I am trying to figure out the "inverse" problem: given time and [a ...
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### Daytime length and sunrise / set cardinal directions

Let me illustrate the question with an example. On Feb 2nd 2022, the sun rises in Los Angeles at cardinal direction 110 and sets in direction 250 (according to timedate website). This means that the ...
• 21
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### How long is the sunrise (or sunset) on North (or South) Pole? [duplicate]

I wonder how to calculate the duration of the Sun crossing the line of the horizon on equinox on Pole. For equator I used this formula: $t = \frac{2 \times p}{\cos(\phi) \times u}$, where $u$ - is ...
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1 vote
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### What is the relationship between the shape of the analemma and the sun's azimuth at sunset at a given latitude?

I want to know how the sun's azimuth at sunset changes over the course of a year. At first, I thought it would have purely sinusoidal motion, hitting its maxima and minima at the solstices, and ...
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1 vote
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### Tracking the Sun from Sunrise in the East to Sunset in the West

Is there a Correct way to mathematically allocate GPS/location of Azimuth Degrees ? EG: In the Southern Hemisphere, if North is 0 degrees, for say Sydney is direct East 90 or -90 degrees ? Then what ...
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### Straightforward derivation of the sunrise equation

I'm looking for a reasonably straightforward derivation of the sunrise equation$$\cos\omega=-\tan\phi\tan\delta$$as referenced in the Wikipedia article here. I've dipped into Astronomical Algorithms ...
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### 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 ...
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### Angle the Sun makes with the horizon during sunset

Let's say it is the day of the summer solstice and the Sun is setting at 23.5 degrees declination. I am at let's say, 10 degrees latitude. How would I go about calculating the angle of the Sun below ...
• 103
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### How does one use SPICE to calculate sunrise and sunset?

I've seen it mentioned here that SPICE can be used to calculate sunrise and sunset. How? According to the official documentation, SPICE is used to calculate: Time system conversions Positions of ...
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1 vote
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### Is it easier to see the young moon when it's closer to the sun?

With the naked eye, would it be easier to see the moon when it's close to the sun, because it might reflect some more light (or not, I'm not sure) or farther from the sun because the sun shines ...
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### Does the Time of Sunset (Sunrise) Change Over Time Given a Fixed Location and Consistent Atmospheric Conditions?

Assumming a fixed location, clear skies, and consistent atmospheric conditions, does the sunset (sunrise) time change over time? For example, sunset on February 3, 2021 in Tel-Aviv, Israel, is ...
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### Timing based on upper or lower part of sun/moon

When you time an astronomical event, such as the moon/sun rising above the horizon, do you note the time when the the first sliver breeches the horizon or when the bottom of the moon/sun just becomes ...
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### 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 ...
• 121
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### Does the sun's rising/setting angle change every few months?

When I lived in Darwin, Australia, I noticed that the Sun set in a slightly different direction to the West. In the evenings, I used to sit on a couch and watch TV. There was a huge window to my right ...
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### Why both sunrise and sunset use the position of the sun's upper limb?

It is my understanding, that astronomical moments of both rise and set use the relative position of background object's upper limb to the foreground object's horizon. When were these definitions ...
1 vote
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### Why the earth orbits the sun from X to -X and not the opposite [closed]

I wonder all the time, why the earth orbits the sun as expected from east to west(X to -X) ? It could be different, for example from the west towards the east . What would happen if that were the case?...
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### How to generate times of sunset along a line that crosses a continent?

Would like to avoid using single location iteration of a website that gives time of sunset each date for locations. I want to be able to produce a chart or info-graphic for publishing on a website as ...
1k views

### problems finding rise set and transit times at high latitudes using Meeus' algorithms

I am implementing Jean Meeus' algorithm from his book "Astronomical Algorithms", 2nd ed. for rise, set and transit times in Swift. It seems to provide very good results (no more than 1 ...
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1 vote
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### How to calculate sunrise and sunset on on a given date and location?

I have a given date at any time in future or past eg: 2016-04-23 or 2022-05-12 Now given at any location(lat,lng). How do i find the time of sunrise or sunset.
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### Deducing the hour based on RA

I'm making a technological project. The goal is to write a program that gets an image of the nightsky and predicts the hour in which the photo was taken. I implemented a well-known method using the ...
1 vote
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### How to find how many degrees from the beginning to the end of the sunset?

According to what I what told here there is 0.5 degrees from the beginning the end of the sunset. Unfortunately I didn't understand two things: 1) How can I prove in the simplest way that there'...
5k views

### How long do the phases of sunset take? [duplicate]

How long does it take from the moment the Sun star 'touches' the horizon, to the time it totally disappear? (I'm not talking about the radiation (rays), but just about the appearance of the star by ...
479 views

### Was the Earth-Sun distance ever calculated based on the time difference between night and day?

If we define sunrise and sunset as the time when the center of the Sun goes over the horizon then day time is a little bit shorter than night time because from a single point one cannot see a complete ...
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### Seeing a star near zenith around sunset

I'm recalling while taking a university astronomy class the professor brought a few of us up to the observatory, around sunset. He showed us a star near zenith with the telescope. After we left the ...
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