<p>You can get a rough idea of how large the Earth appears from these two photos:
<a href="https://i.sstatic.net/OS83y.jpg" rel="noreferrer"><img src="https://i.sstatic.net/OS83y.jpg" alt="enter image description here"></a></p>

<p><a href="https://i.sstatic.net/696OK.jpg" rel="noreferrer"><img src="https://i.sstatic.net/696OK.jpg" alt="enter image description here"></a></p>

<p>It's not quite that large, is it?</p>

CC BY-SA 4.0
2018-10-28T15:52:25.670Z
You cannot get any idea of how large/small something looks from photos like these. Obvious counterexample here https://sites.google.com/a/g.clemson.edu/the-mysteriously-massive-moon/
ProfRob
CC BY-SA 4.0
2018-10-28T16:24:25.853Z
And indeed *exactly* these photos have been used by conspiracy theorists to claim that the Earth looks too small for the pictures to have been taken on the moon! e g. http://www.angelfire.com/moon2/xpascal/MoonHoax/ApolloEarth/ApolloEarth.HTM
ProfRob
CC BY-SA 4.0
2018-10-28T17:00:26.783Z
@RobJeffries Good points. It was their comments that I found interesting. Both mentioned how small it appeared. My guess is they knew their descriptions would be told and retold so they may have used more poetically descriptive terms rather than direct objective descriptions like, it looked four times bigger than the moon. So I guess my question really doesn’t have an answer because it asks why someone chose to describe something the way they did. They must have been taken by strong emotions by witnessing such a sight. The metaphorically term of small in a cosmic sense most likely applies too.
Lambda
CC BY-SA 4.0
2018-10-28T22:26:51.073Z
https://photo.stackexchange.com/questions/102426/what-kind-of-lens-is-used-in-this-picture-of-earth
Muze
CC BY-SA 4.0
2018-10-29T09:49:36.253Z
Link to more photos of the Apollo 17 EVA: https://www.hq.nasa.gov/alsj/a17/images17.html#MagB
stackzebra
CC BY-SA 4.0
2018-10-29T23:30:03.837Z
To add to @RobJeffries's comment, [here's another common example](https://lh5.googleusercontent.com/-0OFBVGsCDpc/Ts5vhIRNPuI/AAAAAAAAJMc/EriRwqu2pb8/s402/HitchcockZoom_Micael_Reynaud.gif).
JiK
CC BY-SA 4.0
2018-10-28T10:58:02.697Z
2018-10-28T10:58:02.697Z
stackzebra
<p>If you reduce the scale of the Earth to make it the size of a tennis ball, then the moon would be about the size of a nerf ball (20mm or under an inch), and the moon would be about 7 feet from the Earth.</p>

<p>So you can get a good idea of what the Earth would look like from the Moon: Get a tennis ball and nerf ball set them up 7 ft (2 m) apart put your head next to the nerf ball, and the tennis ball will look about the same size as the Earth would look on the moon</p>

<p><a href="https://www.youtube.com/watch?v=GCTuirkcRwo" rel="nofollow noreferrer">https://www.youtube.com/watch?v=GCTuirkcRwo</a></p>

<p>Now hold up your thumb, cover the tennis ball and imagine "on it [is] everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives".   </p>

CC BY-SA 4.0
2018-10-29T07:53:23.317Z
This isn't really that accurate. As stated in the accepted answer the Earth s diameter is ~3.5 times that of the moon. A tennis ball sized Earth leads to a Moon ball that would have a diameter of ~20 mm, almost half the size of a standard table tennis ball.
Dave
CC BY-SA 4.0
2018-10-29T16:48:52.427Z
I've changed to "nerf ball" as per the source. 20mm is about the right size. I think the scale is 19000000:1
James K
CC BY-SA 4.0
2018-10-29T18:19:32.603Z
Nerf balls come in many shapes and sizes: https://nerf.hasbro.com/en-us/sports
GreenMatt
CC BY-SA 4.0
2018-10-28T08:06:26.993Z
2018-10-29T16:47:14.377Z
2018-10-29T16:47:14.377Z
James K
<p>From the moon, the earth would appear to span across about 2 degree of sky.  If you hold your thumb a few inches in front of your face (or your facemask if you are on the moon), your thumb will block about two degrees of your field of view (Armstrong mentions closing one eye because his thumb is close enough that the different perspective between his two eyes is significant).  So there doesn't seem to be anything too surprising about these statements.</p>

CC BY-SA 4.0
2018-10-29T18:24:14.837Z
A very handy number to remember: A thumb at arm's length spans about 2 degrees of arc. A thumb a few inches in front of an eye would span about 20 degrees of arc.
David Hammen
CC BY-SA 4.0
2018-11-02T01:07:43.883Z
Just to add to my previous comment, if you held your thumb a few inches from your face it would span dozens degrees, not two. This answer is very wrong. Why so many upvotes?
David Hammen
CC BY-SA 4.0
2018-10-28T01:47:27.577Z
2018-10-28T01:47:27.577Z
antlersoft
<p>The average distance <span class="math-container">$D$</span> between the Earth and the Moon is about 385000 km. The Earth's mean radius <span class="math-container">$r_E$</span> is 6371 km while the Moon's mean radius <span class="math-container">$r_M$</span> is 1737 km. This means that when the Earth is seen directly overhead from the Moon, it subtends an angle of <span class="math-container">$2\arcsin\left(\frac{r_E}{D-r_M}\right)$</span>, or 1.9°.</p>

<p>A good rule of thumb is that the "<a href="https://www.ncbi.nlm.nih.gov/pubmed/1762884" rel="nofollow noreferrer">visual angle of the width of the thumb held at arm's length is about 2 degrees</a>." (Specifically, it's 2.12°±0.26° at the joint per the referenced paper.) A typical person could just barely blot out the Earth as seen from the Moon with a naked (not gloved) thumb held at arms length. The angular size of a thumb at arm's length varies from person to person; from the referenced paper the visual size of a thumb held at arm's length varied between 1.23° and 3.20° for the 112 tested subjects.</p>

<p>My thumb at arm's length is 2.45° wide at the middle of the thumbnail, so I could easily blot out the Earth from the surface of the Moon with my thumb at arm's length.</p>

CC BY-SA 4.0
2018-10-29T22:45:49.073Z
2018-10-29T22:45:49.073Z
David Hammen
<p>Watching the moon from earth, it seems to be larger at the horizon than at the sky. This means that optical illusions may play a role here, too. The lack of  reference objects or maybe the different shape of the horizon on moon may also contribute to the apparent size of earth.</p>

CC BY-SA 4.0
2018-10-28T17:05:27.520Z
+1. While optical illusions shouldn't affect Armstrong's thumb, it could explain Irwin's comparison to a marble. I wouldn't compare 4x moon to a marble when I look at it with surroundings visible, but it sure might look like one when surrounded only by the darkness of space and no reference for distance.
jpa
CC BY-SA 4.0
2018-10-28T13:34:12.673Z
2018-10-28T13:34:12.673Z
Hartmut Braun
<p>The Earth is 4 times the diameter of the Moon. The Earth viewed from the Moon will therefore appear to have 4 times the angular diameter of the Moon viewed from the Earth.</p>

<p>The Moon is <em>easily</em> obscured by a thumb at arm's length (by a factor of 3-4).</p>

<p>Now bring your thumb closer (because you can't fully extend your arm in a bulky space suit) and put on the biggest pair of ski gloves you can find.</p>

<p>It is not a great stretch of the imagination to think your thumb, in a spacesuit, would easily obscure something 4 times the size of the Moon.</p>

CC BY-SA 4.0
2018-10-29T09:37:59.110Z
For objects seen from afar, apparent relative sizes are actually more about how large an area of our field of view they cover. A circular object with four times the diameter of another circular object will appear sixteen times larger.
Arthur
CC BY-SA 4.0
2018-10-29T09:44:28.653Z
@Arthur that is true if size means solid angle. I will clarify.
ProfRob
CC BY-SA 4.0
2018-10-29T12:24:59.153Z
Even at ground level you can blot out the entire Earth with your thumb, if you put it close enough to your eye.
aroth
CC BY-SA 4.0
2018-10-29T12:49:26.063Z
@Arthur there is a crucial illusion relating to the horizon involved in size perception: when the moon is setting low over the earth's horizon (from Earth), it appears subjectively (according to some studies) 30-40% larger even though in photos it is objectively the same size.  In space it stands to reason that, thus, objects would appear "at their smallest".
Darren Ringer
CC BY-SA 4.0
2018-10-29T18:16:48.027Z
The Moon is *easily* obscured by a thumb at arm's length because the Moon's angular size as seen from Earth is about half a degree while a thumb at arm's length is about two degrees -- four times the size of the Moon. That is about the same size as the Earth as seen from the Moon. A glove isn't needed.
David Hammen
CC BY-SA 4.0
2018-10-29T18:57:48.057Z
@DavidHammen "Big thumbs" to his friends (or "short arms" ?). My thumb does not quite subtend 2 degrees at arms length. It is 2 cm wide and my eye to thumb length with outstretched arm is 67cm. So 1.7 degrees. It's close - I'll reword.
ProfRob
CC BY-SA 4.0
2018-10-29T20:26:26.483Z
Or perhaps you have small thumbs or long arms. A good rule of thumb is that a man's thumb is about an inch wide.
David Hammen
CC BY-SA 4.0
2018-10-30T01:43:32.393Z
The astronauts weren't tall or fat, and you don't need an outstretched arm (esp. in the Apollo CM) to appreciate the effect.  Time on the moon was too precious for much philosophizing.
amI
CC BY-SA 4.0
2018-10-31T01:57:29.867Z
I guess it would depend on whether the Earth was near the moon's horizon, or at a high angle, which would make it appear smaller.  Still I would imagine it would look big to them, relative to the moon, but relative to their earthbound perception of the Earth, it would appear very, very small.  I'm guessing they were trying to make the latter point?  Good question though--it's the first time I've thought about this!
bob
CC BY-SA 4.0
2018-10-28T08:13:32.263Z
2018-10-29T18:59:53.000Z
2018-10-29T18:59:53.000Z
ProfRob
<p>I have no doubt that we have been to the moon. This question has nothing to do with a moon landing hoax.  But, there are two quotes from two different astronauts regarding the size of the earth as viewed from the moon that are puzzling to me. Both quotes talk about how small the Earth looked. Shouldn’t the Earth look very large when viewed from the moon</p>
<blockquote>
<p>It suddenly struck me that that tiny pea, pretty and blue was the Earth. I put up my thumb, shut one eye and my thumb blotted out the planet Earth. I didn't feel like a giant. I felt very, very small. — Neil Armstong</p>
<p>As we got further and further away it [the Earth] diminished in size. Finally it shrank to the size of a marble, the most beautiful you can imagine. That beautiful, warm living object looked so fragile, so delicate that if you touched it with a finger it would crumble and fall apart. Seeing this has to change a man. — James Irwin</p>
</blockquote>
<p>I know the term large is subjective, but still, the comments seem off. Please let me know what I’m missing.</p>

CC BY-SA 4.0
2018-10-29T17:43:57.983Z
OP, it could be that you think the moon is tiny?  Not so - Earth and Moon are *roughly* the same size.  Kind of a twin planet system.
Fattie
CC BY-SA 4.0
2018-10-29T20:08:15.610Z
@Fattie That doesn't sound right to me. Earth has almost 50 times the volume of the moon (1 trillion km^3 vs. 21 billion km^3).
Kevin
CC BY-SA 4.0
2018-10-29T23:37:58.537Z
@Kevin - Take the cube root of 50 to get the ratio of the Earth's diameter to that of the Moon.
David Hammen
CC BY-SA 4.0
2018-10-29T23:40:16.233Z
@jean - Gloves aren't needed. The Earth as seen from the Moon and a thumb at arm's length are more or less the same size.
David Hammen
CC BY-SA 4.0
2018-10-30T03:00:38.683Z
Hi Kevin. They are *about* the same size objects.  Earth and Jupiter, or the Sun versus the Galaxy, or Saturn versus its moons, are radically different in size.   **My guess is the OP things the moon is a "small" thing.**
Fattie
CC BY-SA 4.0
2018-10-30T04:49:11.753Z
@Fattie Smaller is a comparative adjective and the moon compared to other planetary objects in our solar system is comparatively small.
Lambda
CC BY-SA 4.0
2018-10-30T08:37:28.043Z
Hi @Lambda , there are 10 or so "big" moons in our system, and our Moon moon is one of those 10 "big" moons.  The majority of moons in our system are tiny rocks.  Based on your question, my guess is that you thought our Moon was "a small rock"; so, you assumed (not unreasonably) that Earth would be HUGE when seen in comparison.  In fact this is not the case, they're "about" the same size.  As fully explained in Rob's answer.  Cheers!
Fattie
CC BY-SA 4.0
2018-10-30T10:49:32.457Z
@DavidHammen Gloves! big space suit gloves! Relax, I know it's a matter of point o view, just jesting a little *wink* ;)
jean
<the-moon><observational-astronomy><moonlanding>
Puzzling quotes from astronauts about earth size
Lambda
# Puzzling quotes from astronauts about earth size

(Asked by: username_0 on 2018-10-28)

I have no doubt that we have been to the moon. This question has nothing to do with a moon landing hoax. But, there are two quotes from two different astronauts regarding the size of the earth as viewed from the moon that are puzzling to me. Both quotes talk about how small the Earth looked. Shouldn’t the Earth look very large when viewed from the moon

> It suddenly struck me that that tiny pea, pretty and blue was the Earth. I put up my thumb, shut one eye and my thumb blotted out the planet Earth. I didn't feel like a giant. I felt very, very small. — Neil Armstong
>
> As we got further and further away it [the Earth] diminished in size. Finally it shrank to the size of a marble, the most beautiful you can imagine. That beautiful, warm living object looked so fragile, so delicate that if you touched it with a finger it would crumble and fall apart. Seeing this has to change a man. — James Irwin

I know the term large is subjective, but still, the comments seem off. Please let me know what I’m missing.

**Tags:** the-moon, observational-astronomy, moonlanding

> **Comments:**
> **username_1**: OP, it could be that you think the moon is tiny?  Not so - Earth and Moon are *roughly* the same size.  Kind of a twin planet system.  
> **username_2**: @username_1 That doesn't sound right to me. Earth has almost 50 times the volume of the moon (1 trillion km^3 vs. 21 billion km^3).  
> **username_3**: @username_2 - Take the cube root of 50 to get the ratio of the Earth's diameter to that of the Moon.  
> **username_3**: @username_4 - Gloves aren't needed. The Earth as seen from the Moon and a thumb at arm's length are more or less the same size.  
> **username_1**: Hi username_2. They are *about* the same size objects.  Earth and Jupiter, or the Sun versus the Galaxy, or Saturn versus its moons, are radically different in size.   **My guess is the OP things the moon is a "small" thing.**  
> **username_0**: @username_1 Smaller is a comparative adjective and the moon compared to other planetary objects in our solar system is comparatively small.  
> **username_1**: Hi @username_0 , there are 10 or so "big" moons in our system, and our Moon moon is one of those 10 "big" moons.  The majority of moons in our system are tiny rocks.  Based on your question, my guess is that you thought our Moon was "a small rock"; so, you assumed (not unreasonably) that Earth would be HUGE when seen in comparison.  In fact this is not the case, they're "about" the same size.  As fully explained in Rob's answer.  Cheers!  
> **username_4**: @DavidHammen Gloves! big space suit gloves! Relax, I know it's a matter of point o view, just jesting a little *wink* ;)  

---

## 6 answers

### Answer by username_6 on 2018-10-28. Score: 45 | Accepted answer

The Earth is 4 times the diameter of the Moon. The Earth viewed from the Moon will therefore appear to have 4 times the angular diameter of the Moon viewed from the Earth.

The Moon is *easily* obscured by a thumb at arm's length (by a factor of 3-4).

Now bring your thumb closer (because you can't fully extend your arm in a bulky space suit) and put on the biggest pair of ski gloves you can find.

It is not a great stretch of the imagination to think your thumb, in a spacesuit, would easily obscure something 4 times the size of the Moon.

> **Comments:**
> **username_15**: For objects seen from afar, apparent relative sizes are actually more about how large an area of our field of view they cover. A circular object with four times the diameter of another circular object will appear sixteen times larger.  
> **username_6**: @username_15 that is true if size means solid angle. I will clarify.  
> **username_16**: Even at ground level you can blot out the entire Earth with your thumb, if you put it close enough to your eye.  
> **username_17**: @username_15 there is a crucial illusion relating to the horizon involved in size perception: when the moon is setting low over the earth's horizon (from Earth), it appears subjectively (according to some studies) 30-40% larger even though in photos it is objectively the same size.  In space it stands to reason that, thus, objects would appear "at their smallest".  
> **username_3**: The Moon is *easily* obscured by a thumb at arm's length because the Moon's angular size as seen from Earth is about half a degree while a thumb at arm's length is about two degrees -- four times the size of the Moon. That is about the same size as the Earth as seen from the Moon. A glove isn't needed.  
> **username_6**: @DavidHammen "Big thumbs" to his friends (or "short arms" ?). My thumb does not quite subtend 2 degrees at arms length. It is 2 cm wide and my eye to thumb length with outstretched arm is 67cm. So 1.7 degrees. It's close - I'll reword.  
> **username_3**: Or perhaps you have small thumbs or long arms. A good rule of thumb is that a man's thumb is about an inch wide.  
> **username_18**: The astronauts weren't tall or fat, and you don't need an outstretched arm (esp. in the Apollo CM) to appreciate the effect.  Time on the moon was too precious for much philosophizing.  
> **username_19**: I guess it would depend on whether the Earth was near the moon's horizon, or at a high angle, which would make it appear smaller.  Still I would imagine it would look big to them, relative to the moon, but relative to their earthbound perception of the Earth, it would appear very, very small.  I'm guessing they were trying to make the latter point?  Good question though--it's the first time I've thought about this!  

---

### Answer by username_5 on 2018-10-28. Score: 11

You can get a rough idea of how large the Earth appears from these two photos:
[![enter image description here](https://i.sstatic.net/OS83y.jpg)](https://i.sstatic.net/OS83y.jpg)

[![enter image description here](https://i.sstatic.net/696OK.jpg)](https://i.sstatic.net/696OK.jpg)

It's not quite that large, is it?

> **Comments:**
> **username_6**: You cannot get any idea of how large/small something looks from photos like these. Obvious counterexample here https://sites.google.com/a/g.clemson.edu/the-mysteriously-massive-moon/  
> **username_6**: And indeed *exactly* these photos have been used by conspiracy theorists to claim that the Earth looks too small for the pictures to have been taken on the moon! e g. http://www.angelfire.com/moon2/xpascal/MoonHoax/ApolloEarth/ApolloEarth.HTM  
> **username_0**: @RobJeffries Good points. It was their comments that I found interesting. Both mentioned how small it appeared. My guess is they knew their descriptions would be told and retold so they may have used more poetically descriptive terms rather than direct objective descriptions like, it looked four times bigger than the moon. So I guess my question really doesn’t have an answer because it asks why someone chose to describe something the way they did. They must have been taken by strong emotions by witnessing such a sight. The metaphorically term of small in a cosmic sense most likely applies too.  
> **username_7**: https://photo.stackexchange.com/questions/102426/what-kind-of-lens-is-used-in-this-picture-of-earth  
> **username_5**: Link to more photos of the Apollo 17 EVA: https://www.hq.nasa.gov/alsj/a17/images17.html#MagB  
> **username_8**: To add to @RobJeffries's comment, [here's another common example](https://lh5.googleusercontent.com/-0OFBVGsCDpc/Ts5vhIRNPuI/AAAAAAAAJMc/EriRwqu2pb8/s402/HitchcockZoom_Micael_Reynaud.gif).  

---

### Answer by username_9 on 2018-10-28. Score: 11

If you reduce the scale of the Earth to make it the size of a tennis ball, then the moon would be about the size of a nerf ball (20mm or under an inch), and the moon would be about 7 feet from the Earth.

So you can get a good idea of what the Earth would look like from the Moon: Get a tennis ball and nerf ball set them up 7 ft (2 m) apart put your head next to the nerf ball, and the tennis ball will look about the same size as the Earth would look on the moon

<https://www.youtube.com/watch?v=GCTuirkcRwo>

Now hold up your thumb, cover the tennis ball and imagine "on it [is] everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives".

> **Comments:**
> **username_10**: This isn't really that accurate. As stated in the accepted answer the Earth s diameter is ~3.5 times that of the moon. A tennis ball sized Earth leads to a Moon ball that would have a diameter of ~20 mm, almost half the size of a standard table tennis ball.  
> **username_9**: I've changed to "nerf ball" as per the source. 20mm is about the right size. I think the scale is 19000000:1  
> **username_11**: Nerf balls come in many shapes and sizes: https://nerf.hasbro.com/en-us/sports  

---

### Answer by username_12 on 2018-10-28. Score: 8

From the moon, the earth would appear to span across about 2 degree of sky. If you hold your thumb a few inches in front of your face (or your facemask if you are on the moon), your thumb will block about two degrees of your field of view (Armstrong mentions closing one eye because his thumb is close enough that the different perspective between his two eyes is significant). So there doesn't seem to be anything too surprising about these statements.

> **Comments:**
> **username_3**: A very handy number to remember: A thumb at arm's length spans about 2 degrees of arc. A thumb a few inches in front of an eye would span about 20 degrees of arc.  
> **username_3**: Just to add to my previous comment, if you held your thumb a few inches from your face it would span dozens degrees, not two. This answer is very wrong. Why so many upvotes?  

---

### Answer by username_3 on 2018-10-29. Score: 4

The average distance $D$ between the Earth and the Moon is about 385000 km. The Earth's mean radius $r\_E$ is 6371 km while the Moon's mean radius $r\_M$ is 1737 km. This means that when the Earth is seen directly overhead from the Moon, it subtends an angle of $2\arcsin\left(\frac{r\_E}{D-r\_M}\right)$, or 1.9°.

A good rule of thumb is that the "[visual angle of the width of the thumb held at arm's length is about 2 degrees](https://www.ncbi.nlm.nih.gov/pubmed/1762884)." (Specifically, it's 2.12°±0.26° at the joint per the referenced paper.) A typical person could just barely blot out the Earth as seen from the Moon with a naked (not gloved) thumb held at arms length. The angular size of a thumb at arm's length varies from person to person; from the referenced paper the visual size of a thumb held at arm's length varied between 1.23° and 3.20° for the 112 tested subjects.

My thumb at arm's length is 2.45° wide at the middle of the thumbnail, so I could easily blot out the Earth from the surface of the Moon with my thumb at arm's length.


---

### Answer by username_13 on 2018-10-28. Score: 1

Watching the moon from earth, it seems to be larger at the horizon than at the sky. This means that optical illusions may play a role here, too. The lack of reference objects or maybe the different shape of the horizon on moon may also contribute to the apparent size of earth.

> **Comments:**
> **username_14**: +1. While optical illusions shouldn't affect Armstrong's thumb, it could explain Irwin's comparison to a marble. I wouldn't compare 4x moon to a marble when I look at it with surroundings visible, but it sure might look like one when surrounded only by the darkness of space and no reference for distance.  

---

