<p>Let's get the ball rolling! Hopefully some of these are what you are looking for.</p>
<p><strong>Point light approximation</strong></p>
<blockquote>
<p>I take it the size of the objects are illustrative of apparent magnitude and not the visible size</p>
</blockquote>
<p>This is important, and it does not only appear to the planets. Everything in this image, except the Sun, the Earth, the Milky Way, and to some degree Venus are going to be point lights to the naked eye.</p>
<p>Computer monitors or paper are not very good at illustrating point lights. They have by far too few <a href="https://en.wikipedia.org/wiki/Candela_per_square_metre" rel="nofollow noreferrer">nits</a>.</p>
<p>Instead, brightness is approximated by giving all the stars some visible area, proportional to their brightness. It's a useful approximation, but I would definitely count it as an inaccuracy compared to the naked eye.</p>
<p><strong>Relative size of the Sun and the Earth</strong></p>
<p>The Moon is famously the same relative size in the sky as the Sun. However, in this image, we are viewing the much larger Earth from the same distance, yet it still appears the same size as the Sun. The size of either or both has to be wrong</p>
<p><strong>Sun glare</strong></p>
<p>This image shows glare from the Sun. This will vary a lot depending on your eyes. And if the light form the Sun is blocked out like you propose, none of the solar glare in this image will be visible.</p>
<p><strong>Light from the lunar landscape</strong></p>
<p>Unless you also block out the surface of the Moon, the reflected light is going to severely impact the view.</p>
<p><strong>Smooth edges of objects</strong></p>
<p>Real life has no smooth anti-aliased edges. Cutoffs by planetary discs and stars are very hard, unless an atmosphere is present.</p>
<p><strong>City lights on the dark side of the Earth?</strong></p>
<p><a href="https://space.stackexchange.com/questions/38922/could-apollo-astronauts-see-city-lights-from-the-moon">Apollo astronauts could not see this</a>, but admittedly, it was because of limiting observational conditions. Stellarium like does not simulate this</p>
<p><strong>Image compression artefacts</strong></p>
<p>These screenshots have two kinds of compression artefacts introduced by the JPEG format. Needless to say, these are not present in real life.</p>
<ol>
<li>Banding, due to the limited number of dark colours available in the  <a href="https://en.wikipedia.org/wiki/YCbCr" rel="nofollow noreferrer">YCbCr transform</a> used by JPEG:</li>
</ol>
<p><a href="https://i.sstatic.net/K5fy6.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/K5fy6m.png" alt="jpeg banding" /></a></p>
<ol start="2">
<li>Macroblocks of 8x8 pixels, due to the <a href="https://en.wikipedia.org/wiki/Discrete_cosine_transform" rel="nofollow noreferrer">discrete cosine transform</a></li>
</ol>
<p><strong>Colour space</strong></p>
<p>All the way from the colour handling in Stellarium, to the YCbCr space of JPEG, to how your monitor is calibrated, decisions are made about colour. The end result may be far removed from how they really appear. Notably, Stellarium is likely considerably increasing the saturation of the colours of the Milky Way.</p>
<p><strong>Black level</strong></p>
<p>The black in this image is merely grey. Even the brightest parts of the Milky Way will appear darker than what can be found in the screenshot.</p>
<p><strong>Field of view</strong></p>
<p>&quot;Personally I don't see in rectangles&quot; as a comment says. The human field of vision is not rectangular, and it is almost twice as wide as the 90 degrees in this crop.</p>
<p>Brightness and colour sensitivity is also very different between the centre and edges of human vision.</p>
<p><s><strong>mac status bar</strong>: this is not visible in real life :)</s></p>

CC BY-SA 4.0
2020-10-22T12:40:38.580Z
If the mac status bar is not visible in real life does that mean its made up of dark matter?
Bob516
CC BY-SA 4.0
2020-10-21T14:09:00.383Z
2020-10-21T14:09:00.383Z
SE - stop firing the good guys
<p>I found this depiction on Stellarium of the sky as seen from near the Apollo 12 landing site on January 11, 2131. The earth is the black circle in the arm of the Milky Way.</p>
<p><a href="https://i.sstatic.net/cNTEt.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/cNTEt.jpg" alt="Stellarium depiction as seen from Apollo 12 landing site January 11, 2131" /></a></p>
<p>Here is a similar view with labels.</p>
<p><a href="https://i.sstatic.net/4KZIH.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/4KZIH.jpg" alt="Stellarium depiction as seen from Apollo 12 landing site January 11, 2131" /></a></p>
<p>Assuming a person had a naked eye view of this, and the most of the light coming directly from the sun could be attenuated, what inaccuracies are evident in this image? As I understand it the colors to the Milky Way could not be seen by the naked eye. I take it the size of the objects are illustrative of apparent magnitude and not the visible size. Are there any others?</p>
<p>If the &quot;night-sky&quot; tag is not appropriate because this is not the view from Earth please remove or let me know and I'll remove it.</p>
<p>Here is the full screen shot, at horizontal FOV of 90°.</p>
<p><a href="https://i.sstatic.net/nCqzW.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/nCqzW.jpg" alt="enter image description here" /></a></p>
<p>In regards to the sizes of the sun and the earth, at a narrower FOV Stellarium shows the earth as being substantially bigger than the sun.
<a href="https://i.sstatic.net/dPcV8.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/dPcV8.png" alt="enter image description here" /></a></p>

CC BY-SA 4.0
2020-10-17T23:14:29.650Z
It's an interesting question. Implicit here is that a depiction on a computer screen represented as a screen shot then posted on an internet website then viewed on another screen in the middle of the day or in a well lit room could be sufficiently "accurate" that the inaccuracies could be few enough to list :-) Right now you give no scale for the image, what is the field of view for these rectangular images? Personally I don't see in rectangles (currently I'm not a robot), so there's your first inaccuracy!
uhoh
CC BY-SA 4.0
2020-10-18T02:00:26.377Z
@uhoh I understand. I started with wondering whether the earth would really be a black disc in the middle of the arm of the Milky Way. Then I thought about the arm not colorful to the naked eye. From there I wondered what I might be missing, hence my question. I don't need a precise scientific answer, just general ideas of what might be inaccurate, like the earth and the colors of the Milky Way. If there is no way to reasonably pose this question I will delete it.
Bob516
CC BY-SA 4.0
2020-10-18T02:57:46.327Z
No it's an interesting question! The part about color really asks about simulating [Scotopic and Photopic Vision](https://www.rp-photonics.com/scotopic_and_photopic_vision.html) and of course if a person stared directly into the Sun they wouldn't see much of anything, certainly not be dark-adapted to see stars and planets. So there are different ways to interpret both the accuracy  and realism of a computer rendering. Let's see how people answer.
uhoh
<night-sky><stellarium>
What inaccuracies are in this Stellarium depiction of the sky?
Bob516
# What inaccuracies are in this Stellarium depiction of the sky?

(Asked by: username_0 on 2020-10-17)

I found this depiction on Stellarium of the sky as seen from near the Apollo 12 landing site on January 11, 2131. The earth is the black circle in the arm of the Milky Way.

[![Stellarium depiction as seen from Apollo 12 landing site January 11, 2131](https://i.sstatic.net/cNTEt.jpg)](https://i.sstatic.net/cNTEt.jpg)

Here is a similar view with labels.

[![Stellarium depiction as seen from Apollo 12 landing site January 11, 2131](https://i.sstatic.net/4KZIH.jpg)](https://i.sstatic.net/4KZIH.jpg)

Assuming a person had a naked eye view of this, and the most of the light coming directly from the sun could be attenuated, what inaccuracies are evident in this image? As I understand it the colors to the Milky Way could not be seen by the naked eye. I take it the size of the objects are illustrative of apparent magnitude and not the visible size. Are there any others?

If the "night-sky" tag is not appropriate because this is not the view from Earth please remove or let me know and I'll remove it.

Here is the full screen shot, at horizontal FOV of 90°.

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

In regards to the sizes of the sun and the earth, at a narrower FOV Stellarium shows the earth as being substantially bigger than the sun.
[![enter image description here](https://i.sstatic.net/dPcV8.png)](https://i.sstatic.net/dPcV8.png)

**Tags:** night-sky, stellarium
> **Comments:**
> **username_1**: It's an interesting question. Implicit here is that a depiction on a computer screen represented as a screen shot then posted on an internet website then viewed on another screen in the middle of the day or in a well lit room could be sufficiently "accurate" that the inaccuracies could be few enough to list :-) Right now you give no scale for the image, what is the field of view for these rectangular images? Personally I don't see in rectangles (currently I'm not a robot), so there's your first inaccuracy!  
> **username_0**: @uhoh I understand. I started with wondering whether the earth would really be a black disc in the middle of the arm of the Milky Way. Then I thought about the arm not colorful to the naked eye. From there I wondered what I might be missing, hence my question. I don't need a precise scientific answer, just general ideas of what might be inaccurate, like the earth and the colors of the Milky Way. If there is no way to reasonably pose this question I will delete it.  
> **username_1**: No it's an interesting question! The part about color really asks about simulating [Scotopic and Photopic Vision](https://www.rp-photonics.com/scotopic_and_photopic_vision.html) and of course if a person stared directly into the Sun they wouldn't see much of anything, certainly not be dark-adapted to see stars and planets. So there are different ways to interpret both the accuracy  and realism of a computer rendering. Let's see how people answer.  

---

## 1 answers

### Answer by username_2 on 2020-10-21. Score: 2 | Accepted answer

Let's get the ball rolling! Hopefully some of these are what you are looking for.

**Point light approximation**

> I take it the size of the objects are illustrative of apparent magnitude and not the visible size

This is important, and it does not only appear to the planets. Everything in this image, except the Sun, the Earth, the Milky Way, and to some degree Venus are going to be point lights to the naked eye.

Computer monitors or paper are not very good at illustrating point lights. They have by far too few [nits](https://en.wikipedia.org/wiki/Candela_per_square_metre).

Instead, brightness is approximated by giving all the stars some visible area, proportional to their brightness. It's a useful approximation, but I would definitely count it as an inaccuracy compared to the naked eye.

**Relative size of the Sun and the Earth**

The Moon is famously the same relative size in the sky as the Sun. However, in this image, we are viewing the much larger Earth from the same distance, yet it still appears the same size as the Sun. The size of either or both has to be wrong

**Sun glare**

This image shows glare from the Sun. This will vary a lot depending on your eyes. And if the light form the Sun is blocked out like you propose, none of the solar glare in this image will be visible.

**Light from the lunar landscape**

Unless you also block out the surface of the Moon, the reflected light is going to severely impact the view.

**Smooth edges of objects**

Real life has no smooth anti-aliased edges. Cutoffs by planetary discs and stars are very hard, unless an atmosphere is present.

**City lights on the dark side of the Earth?**

[Apollo astronauts could not see this](https://space.stackexchange.com/questions/38922/could-apollo-astronauts-see-city-lights-from-the-moon), but admittedly, it was because of limiting observational conditions. Stellarium like does not simulate this

**Image compression artefacts**

These screenshots have two kinds of compression artefacts introduced by the JPEG format. Needless to say, these are not present in real life.

1. Banding, due to the limited number of dark colours available in the [YCbCr transform](https://en.wikipedia.org/wiki/YCbCr) used by JPEG:

[![jpeg banding](https://i.sstatic.net/K5fy6m.png)](https://i.sstatic.net/K5fy6.png)

2. Macroblocks of 8x8 pixels, due to the [discrete cosine transform](https://en.wikipedia.org/wiki/Discrete_cosine_transform)

**Colour space**

All the way from the colour handling in Stellarium, to the YCbCr space of JPEG, to how your monitor is calibrated, decisions are made about colour. The end result may be far removed from how they really appear. Notably, Stellarium is likely considerably increasing the saturation of the colours of the Milky Way.

**Black level**

The black in this image is merely grey. Even the brightest parts of the Milky Way will appear darker than what can be found in the screenshot.

**Field of view**

"Personally I don't see in rectangles" as a comment says. The human field of vision is not rectangular, and it is almost twice as wide as the 90 degrees in this crop.

Brightness and colour sensitivity is also very different between the centre and edges of human vision.

~~**mac status bar**: this is not visible in real life :)~~

> **Comments:**
> **username_0**: If the mac status bar is not visible in real life does that mean its made up of dark matter?  

---

