<p>The length of the day would be the same on (almost) every latitude, and just a bit longer than the night. The reason for that is that the planet's star (let's call it 'Sun') is a disk, not a point. So even if the middle of the Sun is below the horizon, part of it might still be above the horizon and it's technically 'day'. For the same reason, the length of an Earth day at <a href="https://en.wikipedia.org/wiki/Equinox" rel="noreferrer">Equinox</a> is slightly more than 12 hours.</p>

<p>At the poles, and a small region around them (depending on the apparent size of the Sun), it will always be day. At the North Pole of the planet, you will always see exactly the northern half of the Sun; the southern half will always be under the horizon. It will still take the Sun exactly the same amount of time to go 'around' the sky 360 degrees as it will on the equator or any other place on the planet.</p>

<p>The <a href="https://en.wikipedia.org/wiki/Equinox#Day_arcs_of_the_Sun" rel="noreferrer">diagrams in the Wikipedia article</a> are a good visualization how <em>every</em> day on such a planet would look like (click to enlarge):</p>

<p><a href="https://i.sstatic.net/ZbdF6.jpg" rel="noreferrer"><img src="https://i.sstatic.net/ZbdF6m.jpg" alt="enter image description here"></a>
<a href="https://i.sstatic.net/uBqsa.jpg" rel="noreferrer"><img src="https://i.sstatic.net/uBqsam.jpg" alt="enter image description here"></a>
<a href="https://i.sstatic.net/qJovK.jpg" rel="noreferrer"><img src="https://i.sstatic.net/qJovKm.jpg" alt="enter image description here"></a></p>

CC BY-SA 3.0
2018-02-07T14:25:27.230Z
Bonus points for noting that the sun is neither a point source nor a planar source.   Subtract   $\epsilon$ points for not mentioning the apparent sunset/rise vs latitude for a very tall person  :-)
Carl Witthoft
CC BY-SA 3.0
2018-02-07T09:38:48.437Z
2018-02-07T10:05:14.977Z
2018-02-07T10:05:14.977Z
Glorfindel
<p>How would the length of day and night change with changes in latitude on a planet with no axial tilt?</p>

<p>Would the poles of the planet be in constant sunlight?</p>

CC BY-SA 3.0
2018-02-07T14:22:55.337Z
If you hold a sphere up to sunlight, I think the answers will become clear.
Carl Witthoft
<the-sun>
How would latitude affect day/night lengths on a planet with no axial tilt?
Pasqueflower
# How would latitude affect day/night lengths on a planet with no axial tilt?

(Asked by: username_0 on 2018-02-07)

How would the length of day and night change with changes in latitude on a planet with no axial tilt?

Would the poles of the planet be in constant sunlight?

**Tags:** the-sun
> **Comments:**
> **username_1**: If you hold a sphere up to sunlight, I think the answers will become clear.  

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## 1 answers

### Answer by username_2 on 2018-02-07. Score: 5 | Accepted answer

The length of the day would be the same on (almost) every latitude, and just a bit longer than the night. The reason for that is that the planet's star (let's call it 'Sun') is a disk, not a point. So even if the middle of the Sun is below the horizon, part of it might still be above the horizon and it's technically 'day'. For the same reason, the length of an Earth day at [Equinox](https://en.wikipedia.org/wiki/Equinox) is slightly more than 12 hours.

At the poles, and a small region around them (depending on the apparent size of the Sun), it will always be day. At the North Pole of the planet, you will always see exactly the northern half of the Sun; the southern half will always be under the horizon. It will still take the Sun exactly the same amount of time to go 'around' the sky 360 degrees as it will on the equator or any other place on the planet.

The [diagrams in the Wikipedia article](https://en.wikipedia.org/wiki/Equinox#Day_arcs_of_the_Sun) are a good visualization how *every* day on such a planet would look like (click to enlarge):

[![enter image description here](https://i.sstatic.net/ZbdF6m.jpg)](https://i.sstatic.net/ZbdF6.jpg)
[![enter image description here](https://i.sstatic.net/uBqsam.jpg)](https://i.sstatic.net/uBqsa.jpg)
[![enter image description here](https://i.sstatic.net/qJovKm.jpg)](https://i.sstatic.net/qJovK.jpg)

> **Comments:**
> **username_1**: Bonus points for noting that the sun is neither a point source nor a planar source.   Subtract   $\epsilon$ points for not mentioning the apparent sunset/rise vs latitude for a very tall person  :-)  

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