<p>In short, you would need a very high resolution photo -- most likely taken through a telescope -- to identify any surface features on the moon by their effect on the limb (that is, the edge of the moon against the sun).</p>
<p>In the photo you posted, the moon is about 500 pixels wide. The moon's diameter is around 1,738 km, so in this photo, each pixel represents a bit less than 3.5 km. The tallest mountain on the moon is Mons Huygens, which has about 4.7 km of topographic prominence (that is, its height above its surroundings). So the biggest mountain on the moon is about 1.3 pixels tall -- and most of the moon is much flatter than that. Surface relief features of the moon just aren't big enough to be identifiable at this scale.</p>
<p>You probably could see some of the larger features of the moon's limb if you took a photo of the moon with enough magnification that it completely fills the frame of a really good 20 megapixel camera, where you'd be looking at something like 350 meters per pixel.</p>
<p>However, there <em>is</em> a phenomenon that shows the surface features of the moon even if we can't see them directly. In the few seconds as the edge of the moon exactly overlaps the very edge of the sun, we can see tiny specks of light with dark between them. This is known as &quot;Baily's Beads&quot;:</p>
<p><a href="https://i.sstatic.net/DHQWT.jpg" rel="noreferrer"><img src="https://i.sstatic.net/DHQWT.jpg" alt="Baily's Beads from the solar eclipse of August 21, 2017" /></a></p>
<p>The dark spots are higher points that block the view of the sun, while the lights are low spots or craters that allow the sun to peek through. They are named for astronomer Francis Baily, vice president of the British Royal Astronomical Society, who in 1836 explained what causes the effect.</p>

CC BY-SA 4.0
2024-03-08T02:15:37.537Z
Observing lunar occultations and also looking at the lunar limb at 50 times magnification, it is very apparent the lunar limb isn't smooth (both the illuminated and dark part (still illuminated by earth shine, unless close to full moon)). [This](https://www.abc.net.au/reslib/201402/r1238512_16397269.jpg) is more representative of what it looks like.
Peter Mortensen
CC BY-SA 4.0
2024-03-08T02:21:31.083Z
Or [this](https://apod.nasa.gov/apod/ap190409.html) (though JPEG always distorts).
Peter Mortensen
CC BY-SA 4.0
2024-03-09T22:17:47.567Z
Those are some really cool photos!
Darth Pseudonym
CC BY-SA 4.0
2024-03-06T19:00:05.007Z
2024-03-06T19:00:05.007Z
Darth Pseudonym
<p>The picture in the OP is most likely a drawing. You can tell by a cartoon-like look of the corona as well as a similarly sterile solar flare on the right.</p>
<p>If you search for actual high-resolution photos of a solar eclipse, you'll find e.g. ref. 1 or ref. 2, where the lunar relief, while being very subtle (due to the mountains being small relative to lunar diameter), is still noticeable.</p>
<p>Also note that in some cases atmospheric distortion (particularly near the horizon) will give you a false relief, as can be seen e.g. in ref. 3.</p>
<p>To illustrate visibility of relief, below I used the image form ref. 1 and a simulation of this eclipse in Stellarium, with a custom 3D model of the Moon. The location and time are not exactly the same, since the source web page doesn't specify them. The two white lines mark the corresponding parts of the lunar rim where you can see similar structures in the bumps.</p>
<p>Stellarium + 3D Moon with relief:</p>
<p><a href="https://i.sstatic.net/H6iPG.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/H6iPG.png" alt="" /></a></p>
<p>Rotated and marked image from ref. 1:</p>
<p><a href="https://i.sstatic.net/p0PHf.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/p0PHf.jpg" alt="" /></a></p>
<h4>References</h4>
<ol>
<li><a href="https://apod.nasa.gov/apod/ap051005.html" rel="nofollow noreferrer">&quot;Annular Solar Eclipse at High Resolution&quot;</a>, Stefan Seip, 2005-10-05.</li>
<li><a href="http://www.zam.fme.vutbr.cz/%7Edruck/Eclipse/Ecl2008m/Tse2008_1250_mo1/0-info.htm" rel="nofollow noreferrer">&quot;High resolution image of inner corona&quot;</a>, Miloslav Druckmüller, 2008-08-01.</li>
<li><a href="https://science.nasa.gov/resource/a-partial-solar-eclipse/" rel="nofollow noreferrer">&quot;A Partial Solar Eclipse&quot;</a>, NASA/Bill Ingalls, 2021-06-10.</li>
</ol>

CC BY-SA 4.0
2024-03-07T09:48:27.870Z
the picture in the OP is pretty close to the huge number of photos produced by amateurs of total eclipses using ordinary cameras, rather than using the specialist equipment needed for 1 or 3 of your references
Tristan
CC BY-SA 4.0
2024-03-07T10:15:36.397Z
The random photo I posted is not the only one, it is one of many.
I simply didn’t and couldn’t publish a hundred photos at once.
 It is impossible to exclude that this photo was retouched, like any other.
 although others differ little in appearance.
There are some minor defects in the images from your links, but it is impossible to say certainly that they are a consequence of the relief, they are more similar to image defects.
Vladimir Orlov
CC BY-SA 4.0
2024-03-07T11:44:16.290Z
@Tristan please give a couple examples that are really confirmed to be photos. If you've just looked at Google Image Search, then you must have gotten lots of drawings, not photos.
Ruslan
CC BY-SA 4.0
2024-03-07T12:21:28.353Z
@VladimirOrlov these "minor defects" correlate with a model, see the updated answer.
Ruslan
CC BY-SA 4.0
2024-03-07T14:12:32.080Z
@Ruslan I'm thinking primarily of one of the ones my dad took of the 2017 eclipse in the US using his DSLR. The one in the OP is definitely a bit more "perfect" than it in a way that might suggest it's been drawn or altered, but that photo of my dad (and the thousands of other such photos produced by amateur photographers with their ordinary cameras)'s is far closer to the OP's than either your examples 1 or 2
Tristan
CC BY-SA 4.0
2024-03-07T14:14:57.100Z
the main reason is that the sort of camera accessible to an ordinary amateur photographer doesn't have anything close to the dynamic range necessary for those sorts of photos
Tristan
CC BY-SA 4.0
2024-03-07T14:34:15.003Z
@Tristan Well, the photo of the corona was taken by Canon 1Ds Mark III, whose dynamic range is not much higher than that of, say, 80D. Instead of relying on some extra dynamic range, the photographer used exposure bracketing. All this is described on the page linked.
Ruslan
CC BY-SA 4.0
2024-03-07T08:43:42.343Z
2024-03-07T12:21:00.383Z
2024-03-07T12:21:00.383Z
Ruslan
<p>I looked at a lot of high-quality images of solar eclipses and noticed the following thing:
In all the photographs I've seen, the lunar disk has a completely clear outline, in which it is impossible to see any irregularities due to the presence of the lunar relief.
Although one should expect them to be visible?</p>
<p><a href="https://i.sstatic.net/Z2SK9.jpg" rel="noreferrer"><img src="https://i.sstatic.net/Z2SK9.jpg" alt="enter image description here" /></a></p>
<p>Source: Times of India - IndiaTimes</p>

CC BY-SA 4.0
2024-03-06T17:28:33.047Z
https://en.wikipedia.org/wiki/Baily%27s_beads
John Doty
CC BY-SA 4.0
2024-03-06T18:06:36.050Z
What is the expected height (in pixels) of the mountains you expect to see?
JohnHoltz
CC BY-SA 4.0
2024-03-06T18:27:03.497Z
@JohnHoltz, I understand what you mean. Give a look to here : https://cs4.pikabu.ru/post_img/big/2015/11/23/6/1448271360_1114270225.jpg
Vladimir Orlov
CC BY-SA 4.0
2024-03-06T22:00:52.030Z
@VladimirOrlov The irregularities in this photo are amplified by the grazing angle of the illumination near the terminator. In your eclipse photo this is just not visible because of the perspective.
Thomas
CC BY-SA 4.0
2024-03-06T23:09:43.873Z
Even a photo of the full mood will show virtually no topography.  If you think you do see some, it's probably the terminator, and the other side will be smooth.
Greg Miller
CC BY-SA 4.0
2024-03-07T00:14:06.833Z
Right @VladimirOrlov The limb appears to be very smooth, just like in the solar eclipse photo.
JohnHoltz
CC BY-SA 4.0
2024-03-07T13:50:25.307Z
If you look at a partial eclipse with enough magnification and good atmospheric seeing, the roughness of the lunar limb against the solar disk is easily discernible.  It is probably harder to detect during a total eclipse when it is silhouetted against the much dimmer solar corona.
antlersoft
CC BY-SA 4.0
2024-03-07T16:16:06.517Z
Where is that image from? It looks like it could be CG.
Matthias
<the-moon><solar-eclipse>
Why is the lunar relief not visible in photographs of solar eclipses?
Vladimir Orlov
# Why is the lunar relief not visible in photographs of solar eclipses?

(Asked by: username_0 on 2024-03-06)

I looked at a lot of high-quality images of solar eclipses and noticed the following thing:
In all the photographs I've seen, the lunar disk has a completely clear outline, in which it is impossible to see any irregularities due to the presence of the lunar relief.
Although one should expect them to be visible?

[![enter image description here](https://i.sstatic.net/Z2SK9.jpg)](https://i.sstatic.net/Z2SK9.jpg)

Source: Times of India - IndiaTimes

**Tags:** the-moon, solar-eclipse

> **Comments:**
> **username_1**: https://en.wikipedia.org/wiki/Baily%27s_beads  
> **username_2**: What is the expected height (in pixels) of the mountains you expect to see?  
> **username_0**: @username_2, I understand what you mean. Give a look to here : https://cs4.pikabu.ru/post_img/big/2015/11/23/6/1448271360_1114270225.jpg  
> **username_3**: @username_0 The irregularities in this photo are amplified by the grazing angle of the illumination near the terminator. In your eclipse photo this is just not visible because of the perspective.  
> **username_4**: Even a photo of the full mood will show virtually no topography.  If you think you do see some, it's probably the terminator, and the other side will be smooth.  
> **username_2**: Right @username_0 The limb appears to be very smooth, just like in the solar eclipse photo.  
> **username_5**: If you look at a partial eclipse with enough magnification and good atmospheric seeing, the roughness of the lunar limb against the solar disk is easily discernible.  It is probably harder to detect during a total eclipse when it is silhouetted against the much dimmer solar corona.  
> **username_6**: Where is that image from? It looks like it could be CG.  

---

## 2 answers

### Answer by username_7 on 2024-03-06. Score: 36

In short, you would need a very high resolution photo -- most likely taken through a telescope -- to identify any surface features on the moon by their effect on the limb (that is, the edge of the moon against the sun).

In the photo you posted, the moon is about 500 pixels wide. The moon's diameter is around 1,738 km, so in this photo, each pixel represents a bit less than 3.5 km. The tallest mountain on the moon is Mons Huygens, which has about 4.7 km of topographic prominence (that is, its height above its surroundings). So the biggest mountain on the moon is about 1.3 pixels tall -- and most of the moon is much flatter than that. Surface relief features of the moon just aren't big enough to be identifiable at this scale.

You probably could see some of the larger features of the moon's limb if you took a photo of the moon with enough magnification that it completely fills the frame of a really good 20 megapixel camera, where you'd be looking at something like 350 meters per pixel.

However, there *is* a phenomenon that shows the surface features of the moon even if we can't see them directly. In the few seconds as the edge of the moon exactly overlaps the very edge of the sun, we can see tiny specks of light with dark between them. This is known as "Baily's Beads":

[![Baily's Beads from the solar eclipse of August 21, 2017](https://i.sstatic.net/DHQWT.jpg)](https://i.sstatic.net/DHQWT.jpg)

The dark spots are higher points that block the view of the sun, while the lights are low spots or craters that allow the sun to peek through. They are named for astronomer Francis Baily, vice president of the British Royal Astronomical Society, who in 1836 explained what causes the effect.

> **Comments:**
> **username_8**: Observing lunar occultations and also looking at the lunar limb at 50 times magnification, it is very apparent the lunar limb isn't smooth (both the illuminated and dark part (still illuminated by earth shine, unless close to full moon)). [This](https://www.abc.net.au/reslib/201402/r1238512_16397269.jpg) is more representative of what it looks like.  
> **username_8**: Or [this](https://apod.nasa.gov/apod/ap190409.html) (though JPEG always distorts).  
> **username_7**: Those are some really cool photos!  

---

### Answer by username_9 on 2024-03-07. Score: 7

The picture in the OP is most likely a drawing. You can tell by a cartoon-like look of the corona as well as a similarly sterile solar flare on the right.

If you search for actual high-resolution photos of a solar eclipse, you'll find e.g. ref. 1 or ref. 2, where the lunar relief, while being very subtle (due to the mountains being small relative to lunar diameter), is still noticeable.

Also note that in some cases atmospheric distortion (particularly near the horizon) will give you a false relief, as can be seen e.g. in ref. 3.

To illustrate visibility of relief, below I used the image form ref. 1 and a simulation of this eclipse in Stellarium, with a custom 3D model of the Moon. The location and time are not exactly the same, since the source web page doesn't specify them. The two white lines mark the corresponding parts of the lunar rim where you can see similar structures in the bumps.

Stellarium + 3D Moon with relief:

[![](https://i.sstatic.net/H6iPG.png)](https://i.sstatic.net/H6iPG.png)

Rotated and marked image from ref. 1:

[![](https://i.sstatic.net/p0PHf.jpg)](https://i.sstatic.net/p0PHf.jpg)

#### References

1. ["Annular Solar Eclipse at High Resolution"](https://apod.nasa.gov/apod/ap051005.html), Stefan Seip, 2005-10-05.
2. ["High resolution image of inner corona"](http://www.zam.fme.vutbr.cz/%7Edruck/Eclipse/Ecl2008m/Tse2008_1250_mo1/0-info.htm), Miloslav Druckmüller, 2008-08-01.
3. ["A Partial Solar Eclipse"](https://science.nasa.gov/resource/a-partial-solar-eclipse/), NASA/Bill Ingalls, 2021-06-10.

> **Comments:**
> **username_10**: the picture in the OP is pretty close to the huge number of photos produced by amateurs of total eclipses using ordinary cameras, rather than using the specialist equipment needed for 1 or 3 of your references  
> **username_0**: The random photo I posted is not the only one, it is one of many. I simply didn’t and couldn’t publish a hundred photos at once.  It is impossible to exclude that this photo was retouched, like any other.  although others differ little in appearance. There are some minor defects in the images from your links, but it is impossible to say certainly that they are a consequence of the relief, they are more similar to image defects.  
> **username_9**: @username_10 please give a couple examples that are really confirmed to be photos. If you've just looked at Google Image Search, then you must have gotten lots of drawings, not photos.  
> **username_9**: @username_0 these "minor defects" correlate with a model, see the updated answer.  
> **username_10**: @username_9 I'm thinking primarily of one of the ones my dad took of the 2017 eclipse in the US using his DSLR. The one in the OP is definitely a bit more "perfect" than it in a way that might suggest it's been drawn or altered, but that photo of my dad (and the thousands of other such photos produced by amateur photographers with their ordinary cameras)'s is far closer to the OP's than either your examples 1 or 2  
> **username_10**: the main reason is that the sort of camera accessible to an ordinary amateur photographer doesn't have anything close to the dynamic range necessary for those sorts of photos  
> **username_9**: @username_10 Well, the photo of the corona was taken by Canon 1Ds Mark III, whose dynamic range is not much higher than that of, say, 80D. Instead of relying on some extra dynamic range, the photographer used exposure bracketing. All this is described on the page linked.  

---

