<p>You know, the first time someone told me this, I was absolutely certain they were confused, ignorant, or otherwise mistaken, and I told him he had his facts wrong. To be precise, we were talking about an observer on the equator. I maintained that the Sun would rise due east and set due west, all year round. He said no.</p>

<p>What gave me pause, though, is that this person was far from ignorant, so maybe the other two appellations didn't fit either. I went home and tried to construct a convincing proof of my side, and in the middle of the night a very simple and convincing proof did come to mind. Except that it was a proof that I was wrong.</p>

<p>Imagine that you're on equator at sunrise on the summer solstice. Due east is along the equator. But the plane of the equator is tilted relative to the Earth's orbit, and the Sun is well above (north) of it. You cannot see it due east at sunrise. It has to be $23.5^\circ$ north of east. (Remember, this is for an observer on the equator.)</p>

<p>By the same token, the Sun must rise $23.5^\circ$ south of east on the winter solstice, and gradually transition between these extremes during the year.</p>

CC BY-SA 3.0
2016-09-10T21:25:25.680Z
There is no such concept as “summer” on the **equator**.
Incnis Mrsi
CC BY-SA 4.0
2023-06-12T02:25:30.343Z
@IncnisMrsi the summer solstice (which is what ganbustine wrote) is the at the same time everywhere on Earth (even though you barely notice it).
RonJohn
CC BY-SA 4.0
2023-06-12T11:38:39.393Z
@RonJohn that’s flatly false: https://www.ga.gov.au/scientific-topics/astronomical/summer-and-winter-solstice
Incnis Mrsi
CC BY-SA 4.0
2023-06-12T11:40:27.457Z
@IncnisMrsi I read your link.  It does not say what you think it says.
RonJohn
CC BY-SA 4.0
2023-06-12T11:43:29.317Z
@IncnisMrsi now here's *my* citation, and a quote. https://www.nationalgeographic.com/science/article/what-is-summer-winter-solstice-answer-might-surprise-you "**Solstices occur at the same time around the world**, but their local times vary with time zones. "  Since the equator is part of the world, it happens there, too.
RonJohn
CC BY-SA 4.0
2023-06-12T13:25:38.127Z
@RonJohn time zones (and time of day in general) are irrelevant. Again, there is *northern* summer ≈ *southern* winter and vice versa. And there are neither northern nor southern seasons on the equator.
Incnis Mrsi
CC BY-SA 4.0
2023-06-12T13:30:01.523Z
@IncnisMrsi "summer" is irrelevant to the fact that there are two solstices, and they happen at the same time all around the world.
RonJohn
CC BY-SA 3.0
2015-01-22T07:38:28.047Z
2015-01-22T07:38:28.047Z
ganbustein
<p>[For this explanation, it's helpful to ignore the slight apparent <span class="math-container">$1^\circ$</span> motion of the Sun throughout the day].</p>
<p>The way I like to think about this is imagine standing at the North Pole in the summer time.  Over the course of a day, all you're going to do is spin in a circle, and the Sun will make a circle around your zenith.  When you're at the one of the poles, your definition of &quot;up&quot; and the Earth's rotational axis are the same.  So, of course, the Sun will appear in every direction throughout the day, including directly North.</p>
<p>If you then move 20° to the South, you have rotated yourself 20° from the Earth's rotational axis.  So the Sun will still make a circle in the sky, but it will no longer be centered on your zenith.  Instead the center will be shifted by the amount you rotated yourself (with respect to the Earth's axis).</p>
<p>If you then move a little further to the South, that circle will begin to intersect the horizon.  But only a small piece of the circle is removed.</p>
<p>To exemplify this, the images below show the path of the Sun through the sky at 90°N, 70°N, and 50°N near the summer solstice.  You can try different values, and other celestial objects using this <a href="https://www.celestialprogramming.com/Sky_Path/" rel="nofollow noreferrer">Sky Path</a> page.</p>
<p>Path of Sun viewed from North Pole:</p>
<p><a href="https://i.sstatic.net/H7DdA.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/H7DdA.png" alt="enter image description here" /></a></p>
<p>Path of Sun viewed from 70deg N.:</p>
<p><a href="https://i.sstatic.net/JMYMJ.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/JMYMJ.png" alt="enter image description here" /></a></p>
<p>Path of Sun viewed from 50deg N.:</p>
<p><a href="https://i.sstatic.net/GegfK.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/GegfK.png" alt="enter image description here" /></a></p>

CC BY-SA 4.0
2023-06-09T17:53:19.887Z
2023-06-09T17:53:19.887Z
Greg Miller
<p>Can someone please explain this phenomenon? A solid explanation seems to be missing from the entire internet. </p>

CC BY-SA 3.0
2016-09-10T21:26:45.843Z
A correct presumption would be: “… the sun rise[s] north of east between the *March* and *September* equinoxes”.
Incnis Mrsi
CC BY-SA 4.0
2023-06-09T18:21:56.557Z
Related: https://astronomy.stackexchange.com/q/39670/16685
PM 2Ring
CC BY-SA 4.0
2023-06-12T02:20:47.037Z
@IncnisMrsi why the assertion that *March* and *September* are the correct equinox names?
RonJohn
CC BY-SA 4.0
2023-06-12T12:23:54.757Z
@RonJohn a search engine can find thousands uses of these “March” and “Septemper” labels. Does any authority (on astronomy) declare this terminology incorrect? Get a basic astronomy textbook (along the lines of https://content.schoolinsites.com/api/documents/a0484a3763764b3bb72ff8b60e3ec9f8.pdf) and see yourself.
Also the adjectives “vernal” and “autumnal” are not inherently incorrect, but their denotation is bound to a hemisphere.
Incnis Mrsi
CC BY-SA 4.0
2023-06-12T12:29:11.653Z
@IncnisMrsi "A **correct presumption** would be"... you need more authority than "a search engine can find thousands uses of...".  (Language has been significantly dumbed down in the past 50+ years.)  While "their denotation is bound to a hemisphere" is better logic, your assertion about the summer solstice is wrong enough that I doubt you about this, too.
RonJohn
CC BY-SA 4.0
2023-06-12T13:17:00.213Z
The “autumnal equinox” comes in March south of the Earth’s equator. Is the titular presumption correct there?
Incnis Mrsi
CC BY-SA 4.0
2023-06-20T10:19:21.100Z
Had to downvote. Not enough context provided. How does the internet fail to explain, what was searched?
Oscar Lanzi
<orbit><the-sun><azimuth>
Why does the sun rise north of east between the vernal and autumnal equinox?
environmentstudent
# Why does the sun rise north of east between the vernal and autumnal equinox?

(Asked by: username_0 on 2015-01-21)

Can someone please explain this phenomenon? A solid explanation seems to be missing from the entire internet.

**Tags:** orbit, the-sun, azimuth
> **Comments:**
> **username_1**: A correct presumption would be: “… the sun rise[s] north of east between the *March* and *September* equinoxes”.  
> **username_2**: Related: https://astronomy.stackexchange.com/q/39670/16685  
> **username_3**: @IncnisMrsi why the assertion that *March* and *September* are the correct equinox names?  
> **username_1**: @RonJohn a search engine can find thousands uses of these “March” and “Septemper” labels. Does any authority (on astronomy) declare this terminology incorrect? Get a basic astronomy textbook (along the lines of https://content.schoolinsites.com/api/documents/a0484a3763764b3bb72ff8b60e3ec9f8.pdf) and see yourself. Also the adjectives “vernal” and “autumnal” are not inherently incorrect, but their denotation is bound to a hemisphere.  
> **username_3**: @IncnisMrsi "A **correct presumption** would be"... you need more authority than "a search engine can find thousands uses of...".  (Language has been significantly dumbed down in the past 50+ years.)  While "their denotation is bound to a hemisphere" is better logic, your assertion about the summer solstice is wrong enough that I doubt you about this, too.  
> **username_1**: The “autumnal equinox” comes in March south of the Earth’s equator. Is the titular presumption correct there?  
> **username_4**: Had to downvote. Not enough context provided. How does the internet fail to explain, what was searched?  

---

## 2 answers

### Answer by username_5 on 2015-01-22. Score: 4

You know, the first time someone told me this, I was absolutely certain they were confused, ignorant, or otherwise mistaken, and I told him he had his facts wrong. To be precise, we were talking about an observer on the equator. I maintained that the Sun would rise due east and set due west, all year round. He said no.

What gave me pause, though, is that this person was far from ignorant, so maybe the other two appellations didn't fit either. I went home and tried to construct a convincing proof of my side, and in the middle of the night a very simple and convincing proof did come to mind. Except that it was a proof that I was wrong.

Imagine that you're on equator at sunrise on the summer solstice. Due east is along the equator. But the plane of the equator is tilted relative to the Earth's orbit, and the Sun is well above (north) of it. You cannot see it due east at sunrise. It has to be $23.5^\circ$ north of east. (Remember, this is for an observer on the equator.)

By the same token, the Sun must rise $23.5^\circ$ south of east on the winter solstice, and gradually transition between these extremes during the year.

> **Comments:**
> **username_1**: There is no such concept as “summer” on the **equator**.  
> **username_3**: @IncnisMrsi the summer solstice (which is what ganbustine wrote) is the at the same time everywhere on Earth (even though you barely notice it).  
> **username_1**: @RonJohn that’s flatly false: https://www.ga.gov.au/scientific-topics/astronomical/summer-and-winter-solstice  
> **username_3**: @IncnisMrsi I read your link.  It does not say what you think it says.  
> **username_3**: @IncnisMrsi now here's *my* citation, and a quote. https://www.nationalgeographic.com/science/article/what-is-summer-winter-solstice-answer-might-surprise-you "**Solstices occur at the same time around the world**, but their local times vary with time zones. "  Since the equator is part of the world, it happens there, too.  
> **username_1**: @RonJohn time zones (and time of day in general) are irrelevant. Again, there is *northern* summer ≈ *southern* winter and vice versa. And there are neither northern nor southern seasons on the equator.  
> **username_3**: @IncnisMrsi "summer" is irrelevant to the fact that there are two solstices, and they happen at the same time all around the world.  

---

### Answer by username_6 on 2023-06-09. Score: 2

[For this explanation, it's helpful to ignore the slight apparent $1^\circ$ motion of the Sun throughout the day].

The way I like to think about this is imagine standing at the North Pole in the summer time. Over the course of a day, all you're going to do is spin in a circle, and the Sun will make a circle around your zenith. When you're at the one of the poles, your definition of "up" and the Earth's rotational axis are the same. So, of course, the Sun will appear in every direction throughout the day, including directly North.

If you then move 20° to the South, you have rotated yourself 20° from the Earth's rotational axis. So the Sun will still make a circle in the sky, but it will no longer be centered on your zenith. Instead the center will be shifted by the amount you rotated yourself (with respect to the Earth's axis).

If you then move a little further to the South, that circle will begin to intersect the horizon. But only a small piece of the circle is removed.

To exemplify this, the images below show the path of the Sun through the sky at 90°N, 70°N, and 50°N near the summer solstice. You can try different values, and other celestial objects using this [Sky Path](https://www.celestialprogramming.com/Sky_Path/) page.

Path of Sun viewed from North Pole:

[![enter image description here](https://i.sstatic.net/H7DdA.png)](https://i.sstatic.net/H7DdA.png)

Path of Sun viewed from 70deg N.:

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

Path of Sun viewed from 50deg N.:

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


---

