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9 votes
5 answers
3k views

At 45°N, how come the Sun rises in a northeasterly direction?

As per title, I'm having trouble understanding how it's possible for a person at 45°N to see the Sun rising in a northeasterly direction for 6 months of the year. Even during the summer solstice, the ...
Adrien Hingert's user avatar
4 votes
1 answer
241 views

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 ...
Geographos's user avatar
6 votes
1 answer
311 views

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, ...
Jacob Miller's user avatar
5 votes
1 answer
1k views

Realistic description of a sunrise viewed from the asteroid belt?

I'm writing a scene for a short story and wanted to describe a sunrise scene acurately. If someone was in some sort of craft in the asteroid belt and their craft was coming out from behind an asteroid,...
AustinFoss's user avatar
4 votes
1 answer
306 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 ...
Moiz khokhar's user avatar
3 votes
1 answer
586 views

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 ...
No-Time-To-Day's user avatar
1 vote
3 answers
147 views

Are there such circumbinary planet configurations that two suns move towards each other by the sky?

Is it possible that suns move towards each other (not necessarily in opposite directions)? Such a configuration would cause interesting dusk and midday light cycles, in my opinion. Basically the ...
ivan866's user avatar
  • 109
1 vote
1 answer
935 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 ...
Skeye High's user avatar
-4 votes
2 answers
704 views

What is the chance that the Sun will not rise tomorrow?

What is the most likely natural astrophysical mechanism for the "Sun not rising tomorrow", consistent with our scientific knowledge today? Background The "sunrise problem - What is the ...
David Bailey's user avatar
2 votes
0 answers
41 views

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 ...
Geographos's user avatar
3 votes
1 answer
407 views

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 ...
Jen's user avatar
  • 73
3 votes
0 answers
53 views

reason for different location of sun when rising in the morning [duplicate]

Observed from the same geographical location, why does the sun rises from different points on the horizon during different parts of the year? Thank you.
Janiik N.'s user avatar
3 votes
2 answers
1k views

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 ...
Maron's user avatar
  • 131
3 votes
1 answer
143 views

New moon rise same spot on horizon as sunrise, almost same time [closed]

I witnessed the new moon rise just ahead of a sunrise at the very same spot on the horizon. How often could I plan on looking for that occurrence again?
Ruby Moseley's user avatar
1 vote
1 answer
122 views

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 ...
Peter's user avatar
  • 1,033
3 votes
1 answer
354 views

Mean Sunrise Time

How did the author arrive to these numbers? How did he take the $\tan(\log(14 \deg 26 \text{ minutes}))$? I tried many times but I am not reaching to his numbers.
hamzeh musmar's user avatar
3 votes
1 answer
1k views

Why does sun rise further north of where it does any other time of year? I know rises differently depending on the season but this is like never seen [duplicate]

I’ve lived in the outskirts of the city (San Diego). The sun obviously rises in the same place every morning and changes a little as the year progresses. Now it is so far to the left of my normal view ...
Mr. Manfredjensenjen's user avatar
2 votes
2 answers
105 views

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 ...
Tobias Leupold's user avatar
1 vote
1 answer
124 views

What is the "sunrise equation" for non-constant declination component?

The standard Sunrise Equation (refraction neglected) is this: $$ \cos(\text{hour angle}) = \tan(\text{declination})\tan(\text{latitude}) $$ This equation - which really has nothing to do with the Sun ...
d_e's user avatar
  • 1,667
1 vote
2 answers
909 views

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 ...
ETL's user avatar
  • 113
4 votes
2 answers
1k views

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 ...
Chris Gunawardena's user avatar
4 votes
1 answer
386 views

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 ...
mark03's user avatar
  • 43
2 votes
0 answers
86 views

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 ...
Rob's user avatar
  • 21
2 votes
0 answers
57 views

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 ...
ALiCe P.'s user avatar
  • 1,017
4 votes
1 answer
126 views

Difference in Sunrise times between Horizons and NOAA

I used the NOAA solar calculator at https://gml.noaa.gov/grad/solcalc/ to generate the sunrise time for today. ...
Pradyumna's user avatar
  • 171
6 votes
1 answer
550 views

Can stars really be seen after sunrise from Mount Everest?

I came across this image taken on the "Balcony" at over 27,000 ft (8,200 m) elevation, beneath the summit of Mount Everest. So many stars can be seen on it even though the Sun has risen. Do ...
user avatar
0 votes
2 answers
99 views

Given a location and a time on another planet, how do you determine how many hours before or after sunrise is it there?

I'm actually not so much interested in sunrise/sunset times. What I want to know is how to relate local planetary coordinates (e.g., planetary lat/lon) to, for example, heliocentric coordinates at a ...
bob's user avatar
  • 11
1 vote
1 answer
65 views

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 ...
The Raptor's user avatar
5 votes
1 answer
2k views

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 ...
Peter's user avatar
  • 1,033
0 votes
0 answers
58 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 ...
patchie's user avatar
  • 101
2 votes
2 answers
830 views

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 ...
I Love Math's user avatar
3 votes
1 answer
325 views

Is it safe to look at an annular eclipse during sunrise? [duplicate]

I'm lucky enough to be where an annular eclipse will happen at the same time as sunrise. Usually, it's dangerous to look at an eclipse directly. However, the sun appears much less bright at sunrise. ...
Half's user avatar
  • 41
0 votes
1 answer
85 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, ...
Reckless Glacier's user avatar
2 votes
1 answer
436 views

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 ...
phil5's user avatar
  • 61
2 votes
1 answer
2k views

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 ...
DDS's user avatar
  • 137
3 votes
1 answer
33 views

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 ...
Bookaholic's user avatar
  • 1,559
17 votes
6 answers
13k views

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 ...
happybuddha's user avatar
2 votes
1 answer
439 views

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 ...
user avatar
1 vote
1 answer
91 views

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?...
Eisenbiegler's user avatar
7 votes
1 answer
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 ...
Ugo's user avatar
  • 181
1 vote
1 answer
1k views

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.
Suresh Chaudhari's user avatar
3 votes
2 answers
567 views

Is the equinox absolutely true east everywhere?

I've read that only only in the equinoxes do you get to see the sun rise in the exact east regardless where you might happen to be. However I think this is not absolutely true everywhere, but only in ...
user avatar
5 votes
1 answer
461 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 ...
quarague's user avatar
  • 191
3 votes
0 answers
61 views

Would Martian sunrise/sunset look the same at the Thaumasia Plateau as the rovers' photographs?

If observing the sunrise or sunset, with the naked eye, from the Thaumasia Plateau (app. 260°, -10°), 6 kilometers above Mars elevation zero, would it have the same blue hue as the images of the ...
Bob516's user avatar
  • 1,489
3 votes
1 answer
284 views

How long for the sun to traverse its diameter at the pole?

As the sun rises once per year at the north/south pole, the time taken to rise (and set) must also take significantly more time to complete to rise (and set). How long does this take at either pole? ...
Shhhh's user avatar
  • 31
4 votes
2 answers
444 views

Sunrise and sunset times when compared between the vernal and autumnal equinoxes

Why is it that sunrise and sunset occur at different times when compared between the vernal and autumnal equinoxes? Consider Pontianak, Indonesia, 0 deg N, for simplicity. Timeanddate.com gives ...
astroviewer's user avatar
2 votes
1 answer
184 views

Solar azimuth for celtic fire festivals

I am pretty new to astronomy, and I have fallen down rabbit hole creating a new Metonic calendar in Javascript. As part of this I would like to calculate when the sun is half way between a solstice ...
Mark Jones's user avatar
7 votes
2 answers
172 views

Daylight Time Expansion

I live in northern hemisphere around 44th latitude. Starting from Winter Solstice, December 21, 2018 the duration of daylight is naturally increasing. What I observe, however, is that the duration ...
Cowboy Trader's user avatar
0 votes
1 answer
398 views

Sunrise - from earth - sun position or when sun rays reaches earth?

Time for the sun rays to reach earth is approximately 8 mins. If time of the sun rise is 7:30 - which time is this? Time when sun rays reaches earth or time when earth and sun comes into correct ...
FrenkyB's user avatar
  • 103
1 vote
0 answers
52 views

What's the time in which the sun rises? [duplicate]

What's the time the sun takes in order to rise? (The time in which the solar disk crosses the horizon) How does this time depend on local latitude and the sun's declination? Assume that we're at sea ...
A. Sandu's user avatar