<p>The Earth's equator is at an approximate 23.4 degree angle to the plain of its orbit around the Sun. That means that to an Earth-bound observer the Sun appears to move north and south of the celestial equator (which is merely the projection of the Earth's equator on to the sky) during the course of the year.</p>

<p>In fact this is what gives us the seasons - so in the the Sun is at maximum northern declination (the equivalent of latitude when projected on to the sky) at the time of the Summer Solstice (around 21 June - hence summer in the northern hemisphere) and at maximum southern declination at the time of the winter solstice (around 21 December - hence northern winter). </p>

<p>But this movement also means different rising and setting points - in the Northern hemisphere the Sun's rise is between north and ast in the summer and between south and east in the winter (unless, that is, you are within the Artic circle in which case it will not set/rise at all for at least some period in the summer and winter).</p>

<p>There are a variety of online tools that show you this effect - this one: <a href="https://www.timeanddate.com/sun/iraq/baghdad?month=12&amp;year=2017" rel="nofollow noreferrer">https://www.timeanddate.com/sun/iraq/baghdad?month=12&amp;year=2017</a> - shows that in Baghdad the sun rises - in 2017 - at 61 degrees East on 21 June and at 118 degrees East on 21 December - a difference of 58 degrees.</p>

CC BY-SA 3.0
2017-06-17T19:49:47.117Z
Thank you! Is 56.8 a permanent degree? How do you get it, i thought it should be 46.8- 2x23.4?
Kiril Mladenov
CC BY-SA 3.0
2017-06-18T11:11:47.310Z
you are right, bad maths from me. I have edited it, but in fact, thinking about this it may mean the angle between where the sun rises and sets, not the azimuth (height in sky) - I shall research this a bit further.
adrianmcmenamin
CC BY-SA 3.0
2017-06-18T14:26:31.973Z
yes, I do - I realised that after I'd posted it and forgot to update
adrianmcmenamin
CC BY-SA 3.0
2017-06-17T12:58:28.737Z
2017-06-18T14:34:40.550Z
2017-06-18T14:34:40.550Z
adrianmcmenamin
<p><a href="https://i.sstatic.net/xhpO6.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/xhpO6.jpg" alt="enter image description here"></a></p>

<p>How should I understand this 59 degree mentioned below, what does it mean? I could not get it. The photo is a diagram from an article dedicated to the invention of the ecliptic. The photo is from my tablet (the title could be seen)</p>

CC BY-SA 3.0
2017-06-16T21:00:31.517Z
I think this question is not a duplicate, but has been answered in a very similar way here https://astronomy.stackexchange.com/questions/2408/why-is-twilight-longer-in-summer-than-winter-and-shortest-at-the-equinox  The circle in your picture is the green circle in the linked answer.
AtmosphericPrisonEscape
CC BY-SA 3.0
2017-06-17T05:58:03.747Z
I see, so that is a proection of the horizon and the different sun positions througn the year. Thank you! But how is the angle determined? What is the science behind this 59 degree?
Kiril Mladenov
<orbit><observational-astronomy>
Can someone explain me this diagram from an article?
Kiril Mladenov
# Can someone explain me this diagram from an article?

(Asked by: username_0 on 2017-06-16)

[![enter image description here](https://i.sstatic.net/xhpO6.jpg)](https://i.sstatic.net/xhpO6.jpg)

How should I understand this 59 degree mentioned below, what does it mean? I could not get it. The photo is a diagram from an article dedicated to the invention of the ecliptic. The photo is from my tablet (the title could be seen)

**Tags:** orbit, observational-astronomy

> **Comments:**
> **username_1**: I think this question is not a duplicate, but has been answered in a very similar way here https://astronomy.stackexchange.com/questions/2408/why-is-twilight-longer-in-summer-than-winter-and-shortest-at-the-equinox  The circle in your picture is the green circle in the linked answer.  
> **username_0**: I see, so that is a proection of the horizon and the different sun positions througn the year. Thank you! But how is the angle determined? What is the science behind this 59 degree?  

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## 1 answers

### Answer by username_2 on 2017-06-17. Score: 1

The Earth's equator is at an approximate 23.4 degree angle to the plain of its orbit around the Sun. That means that to an Earth-bound observer the Sun appears to move north and south of the celestial equator (which is merely the projection of the Earth's equator on to the sky) during the course of the year.

In fact this is what gives us the seasons - so in the the Sun is at maximum northern declination (the equivalent of latitude when projected on to the sky) at the time of the Summer Solstice (around 21 June - hence summer in the northern hemisphere) and at maximum southern declination at the time of the winter solstice (around 21 December - hence northern winter).

But this movement also means different rising and setting points - in the Northern hemisphere the Sun's rise is between north and ast in the summer and between south and east in the winter (unless, that is, you are within the Artic circle in which case it will not set/rise at all for at least some period in the summer and winter).

There are a variety of online tools that show you this effect - this one: <https://www.timeanddate.com/sun/iraq/baghdad?month=12&year=2017> - shows that in Baghdad the sun rises - in 2017 - at 61 degrees East on 21 June and at 118 degrees East on 21 December - a difference of 58 degrees.

> **Comments:**
> **username_0**: Thank you! Is 56.8 a permanent degree? How do you get it, i thought it should be 46.8- 2x23.4?  
> **username_2**: you are right, bad maths from me. I have edited it, but in fact, thinking about this it may mean the angle between where the sun rises and sets, not the azimuth (height in sky) - I shall research this a bit further.  
> **username_2**: yes, I do - I realised that after I'd posted it and forgot to update  

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