<p>If I do a quick Google search for <code>amsterdam sunrise</code>, I immediately get the time back: <code>6:42 AM</code>.</p>

<p>How is this time calculated?</p>

<p>(I mean how it is really calculated, not how Google get it, with is probably from a table. Of course I mean sunrises and sunsets in the future, not from the past. $:)$)</p>

CC BY-SA 3.0
2016-08-25T20:02:19.403Z
Do you know about the [sunrise equation](https://en.wikipedia.org/wiki/Sunrise_equation)? Scroll down to [the bottom](https://en.wikipedia.org/wiki/Sunrise_equation#Calculate_sunrise_and_sunset).
HDE 226868
CC BY-SA 3.0
2016-08-25T20:11:22.317Z
Thanks, no. From what I read I can calculate $\omega_o = \text{acos}{(-\tan(\phi)\tan(\delta))}$ with in my case $\phi = 50^{\circ}$. How do I get the value of $\delta$ and how do I convert $\omega_o$ to HH:MM (hours and minutes)? Thanks in advance.
Kevin
CC BY-SA 3.0
2016-08-25T20:17:26.467Z
For $\delta$, see [here](https://en.wikipedia.org/wiki/Position_of_the_Sun#Calculations). You just need to find the solar declination of the day. $\omega_o$ is a spatial coordinate, not a length of time. For the date, you need to do a bunch of intermediate calculations, then find the [Julian date](https://en.wikipedia.org/wiki/Julian_day).
HDE 226868
CC BY-SA 3.0
2016-09-02T11:56:11.387Z
Yes, that's what I meant to ask. 
Kevin
<the-sun><time>
How is the time of sunrise and sunset determined?
Kevin
# How is the time of sunrise and sunset determined?

(Asked by: username_0 on 2016-08-25)

If I do a quick Google search for `amsterdam sunrise`, I immediately get the time back: `6:42 AM`.

How is this time calculated?

(I mean how it is really calculated, not how Google get it, with is probably from a table. Of course I mean sunrises and sunsets in the future, not from the past. $:)$)

**Tags:** the-sun, time

> **Comments:**
> **username_1**: Do you know about the [sunrise equation](https://en.wikipedia.org/wiki/Sunrise_equation)? Scroll down to [the bottom](https://en.wikipedia.org/wiki/Sunrise_equation#Calculate_sunrise_and_sunset).  
> **username_0**: Thanks, no. From what I read I can calculate $\omega_o = \text{acos}{(-\tan(\phi)\tan(\delta))}$ with in my case $\phi = 50^{\circ}$. How do I get the value of $\delta$ and how do I convert $\omega_o$ to HH:MM (hours and minutes)? Thanks in advance.  
> **username_1**: For $\delta$, see [here](https://en.wikipedia.org/wiki/Position_of_the_Sun#Calculations). You just need to find the solar declination of the day. $\omega_o$ is a spatial coordinate, not a length of time. For the date, you need to do a bunch of intermediate calculations, then find the [Julian date](https://en.wikipedia.org/wiki/Julian_day).  
> **username_0**: Yes, that's what I meant to ask.   

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## 0 answers

