<p>The need to distinguish between these potato-shaped and spherical moons hasn't arisen. As such, there aren't two different words to designate these two types of moons. And as long as the community of astronomers who study natural satellites doesn't feel the need for there to be an extra category, there likely won't be one created preemptively. </p>

<p>Perhaps, one day, we will discover that potato-shape and spherical satellites form in very different ways, of have very different properties (not just esthetic). Then the case might be made to sort them into two different categories. </p>

<p>On a side-note, defining arbitrary categories is never trivial. How spherical is spherical? The boundary has to be set somewhere, but there always will be edge cases where an object could reasonably fall in either category. </p>

CC BY-SA 4.0
2020-01-30T14:27:55.237Z
A better definition perhaps would be 'differentiated' rather than 'spherical'. Phobos is a bit spherical too, but it's an asteroid and partially hollow. I'm talking about planetary-mass differentiated moons. These are our Earth's moon of course, the Galilean Moons, the seven spherical moons of Saturn, the five spherical moons of Uranus, Neptune's moon Triton, Pluto's moon Charon and possibly Eris' moon Dysnomia (of which we don't know whether it's spherical or not).
user30007
CC BY-SA 4.0
2020-01-30T13:55:32.350Z
2020-01-30T13:55:32.350Z
usernumber
<p>Apparently not! From Space.com's <a href="https://www.space.com/40653-saturns-weird-moon-shapes-explained.html" rel="nofollow noreferrer">Here's Why Saturn's Inner Moons Are Shaped Like Ravioli and Potatoes</a></p>
<blockquote>
<p>The odd shapes of Saturn's inner moons, which resemble objects ranging from ravioli to potatoes, may be due to mergers of tiny moonlets, a new study finds.</p>
<p>The new finding may help to explain how moons in general may form, researchers said in a new paper describing the work.</p>
</blockquote>
<p>The paper in 21-May-2018 Nature Astronomy is <a href="https://www.nature.com/articles/s41550-018-0471-7" rel="nofollow noreferrer">The peculiar shapes of Saturn’s small inner moons as evidence of mergers of similar-sized moonlets</a> (<a href="https://arxiv.org/abs/1805.08682" rel="nofollow noreferrer">arXiv</a>, <a href="https://www.slideshare.net/sacani/the-peculiar-shapes-of-saturns-small-inner-moons-as-evidence-of-mergers-of-similarsized-moonlets" rel="nofollow noreferrer">slideshare</a>) so <strong>these are definitely considered to be non-spherical moons</strong> made from mergers of &quot;moonlets&quot;.</p>
<p><a href="https://i.sstatic.net/H0azO.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/H0azO.jpg" alt="enter image description here" /></a></p>
<p>More (cropped) images of Pan from the NASA News item <a href="https://solarsystem.nasa.gov/news/13005/cassini-reveals-strange-shape-of-saturns-moon-pan/" rel="nofollow noreferrer">Cassini Reveals Strange Shape of Saturn's Moon Pan</a></p>
<p><a href="https://i.sstatic.net/JT0AE.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/JT0AE.png" alt="enter image description here" /></a> <a href="https://i.sstatic.net/1J0tI.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/1J0tI.png" alt="enter image description here" /></a></p>

CC BY-SA 4.0
2020-01-30T14:28:39.273Z
The question is whether they should fall into the same category. I gonna adjust my question.
user30007
CC BY-SA 4.0
2020-01-30T14:31:24.640Z
@user30007 you have two answers now, it is strongly discouraged to change the question once people take the time to post answers. These **are considered moons** by astronomers, period. Also, a "should they" question solicits answers that are primarily opinion-based and therefore not appropriate for Stack Exchange. Instead of changing this question which would probably result in it being rolled back anyway, why not ask a follow-up question. You can link back here for background, and ask something like "Why...?"
uhoh
CC BY-SA 4.0
2020-01-30T14:33:57.933Z
Too late, sorry. But I don't think it's the end of the world if I change "spherical" to "differentiated".
user30007
CC BY-SA 4.0
2020-01-30T14:38:15.843Z
@user30007 no it's not too late, I've rolled back. Seriously you should not change a question like that once answers have been posted. That's not how the site operates. The best way is to move forward and ask a new question about differentiated satellites and link back here. Next time you'll be more careful and write the question that you want answered the first time.
uhoh
CC BY-SA 4.0
2020-01-30T14:43:17.973Z
I don't need to post it again for I've wrote that Phobos and Ganymede being in the same category is weird. One should conclude that I ain't speaking of tiny spherical moonlets but of planetary-mass moons. It is obvious. May I change the text of the question (not the question itself) to add "differentiated"?
user30007
CC BY-SA 4.0
2020-01-30T14:48:57.723Z
@user30007 I'm not a moderator, anyone with 10k reputation can edit and/or roll back anyone else's posts. I just wanted to let you know that there's no such thing as "too late." The text of the question is also the question itself (this isn't Quroa) so we shouldn't change one so that it doesn't match the other. I won't edit further but I'll mention again that asking "should" can get your question closed as looking for answers that are primarily opinion-based *as also mentioned* in the first comment under your question.
uhoh
CC BY-SA 4.0
2020-01-30T14:56:58.480Z
I meant that I've too late seen your advice not to change my question. The question also is whether there's a distinction between spherical differentiated moons and irregular satellites.
user30007
CC BY-SA 4.0
2020-01-30T14:58:08.910Z
@user30007 okay go for it
uhoh
CC BY-SA 4.0
2020-01-30T13:46:43.673Z
2020-01-30T13:52:42.307Z
2020-06-17T09:47:40.653Z
uhoh
<p>Since Titan and Ganymede fall into the same category as Deimos and Phobos or the components of planetary rings, the category of moons, it's like if all asteroids were considered planets. Tiny irregular satellites are called 'moonlets' but still fall into the category of moons.</p>

<p>Is there any distinction between the natural satellites and should there be one? From my point of view, only equilibrium-shaped spherical moons should be considered moons. While natural satellites are all satellites, the spherical ones should be moons. Otherwise it would be extremely weird that Deimos and Phobos fall into the same category as our Moon or the Galilean Moons. For example, Pluto should be considered having five natural satellites, and one of them (Charon) is a moon.</p>

CC BY-SA 4.0
2020-01-30T13:45:29.380Z
"Should there be one?" is a rather subjective question. There still are people upset about the fact that Pluto got its own category of celestial bodies.
usernumber
CC BY-SA 4.0
2020-01-30T14:30:11.217Z
Pluto and Eris are planets and the IAU's definition is silly and wrong, but that's another topic.
user30007
CC BY-SA 4.0
2020-01-30T17:23:25.487Z
I don't see how this can be answered in a reasonable way.  Every answer would start "in my opinion". There's no good reason why potato shaped satellites should or should not be called "moons", any more than there is a reason for feline shaped animals to be called "cats"
James K
CC BY-SA 4.0
2020-01-30T19:36:05.517Z
@JamesK What's wrong with opinions? There are indeed good reasons to consider or not consider irregular satellites moons, or all asteroids planets.
user30007
CC BY-SA 4.0
2020-01-31T03:23:45.683Z
@user30007 re "What's wrong with opinions?" you might start by reading [ask], and follow up by reading our [guidelines for great subjective questions](http://blog.stackoverflow.com/2010/09/good-subjective-bad-subjective/) and SE's blog post about [how real questions have answers](http://blog.stackoverflow.com/2011/01/real-questions-have-answers/). One of the standard closure options is for questions that invite primarily opinion-based answers. Hope this helps :-)
Chappo Hasn't Forgotten
CC BY-SA 4.0
2020-11-17T03:37:21.813Z
I wonder if one could consider rephrasing this question in such a way that it could be reopened?
uhoh
<natural-satellites><geology><definition><galilean-moons><moonlet>
Should only spherical satellites be considered 'moons'?
user30007
# Should only spherical satellites be considered 'moons'?

(Asked by: username_0 on 2020-01-30)

Since Titan and Ganymede fall into the same category as Deimos and Phobos or the components of planetary rings, the category of moons, it's like if all asteroids were considered planets. Tiny irregular satellites are called 'moonlets' but still fall into the category of moons.

Is there any distinction between the natural satellites and should there be one? From my point of view, only equilibrium-shaped spherical moons should be considered moons. While natural satellites are all satellites, the spherical ones should be moons. Otherwise it would be extremely weird that Deimos and Phobos fall into the same category as our Moon or the Galilean Moons. For example, Pluto should be considered having five natural satellites, and one of them (Charon) is a moon.

**Tags:** natural-satellites, geology, definition, galilean-moons, moonlet

> **Comments:**
> **username_1**: "Should there be one?" is a rather subjective question. There still are people upset about the fact that Pluto got its own category of celestial bodies.  
> **username_0**: Pluto and Eris are planets and the IAU's definition is silly and wrong, but that's another topic.  
> **username_2**: I don't see how this can be answered in a reasonable way.  Every answer would start "in my opinion". There's no good reason why potato shaped satellites should or should not be called "moons", any more than there is a reason for feline shaped animals to be called "cats"  
> **username_0**: @username_2 What's wrong with opinions? There are indeed good reasons to consider or not consider irregular satellites moons, or all asteroids planets.  
> **username_3**: @username_0 re "What's wrong with opinions?" you might start by reading [ask], and follow up by reading our [guidelines for great subjective questions](http://blog.stackoverflow.com/2010/09/good-subjective-bad-subjective/) and SE's blog post about [how real questions have answers](http://blog.stackoverflow.com/2011/01/real-questions-have-answers/). One of the standard closure options is for questions that invite primarily opinion-based answers. Hope this helps :-)  
> **username_4**: I wonder if one could consider rephrasing this question in such a way that it could be reopened?  

---

## 2 answers

### Answer by username_1 on 2020-01-30. Score: 1

The need to distinguish between these potato-shaped and spherical moons hasn't arisen. As such, there aren't two different words to designate these two types of moons. And as long as the community of astronomers who study natural satellites doesn't feel the need for there to be an extra category, there likely won't be one created preemptively.

Perhaps, one day, we will discover that potato-shape and spherical satellites form in very different ways, of have very different properties (not just esthetic). Then the case might be made to sort them into two different categories.

On a side-note, defining arbitrary categories is never trivial. How spherical is spherical? The boundary has to be set somewhere, but there always will be edge cases where an object could reasonably fall in either category.

> **Comments:**
> **username_0**: A better definition perhaps would be 'differentiated' rather than 'spherical'. Phobos is a bit spherical too, but it's an asteroid and partially hollow. I'm talking about planetary-mass differentiated moons. These are our Earth's moon of course, the Galilean Moons, the seven spherical moons of Saturn, the five spherical moons of Uranus, Neptune's moon Triton, Pluto's moon Charon and possibly Eris' moon Dysnomia (of which we don't know whether it's spherical or not).  

---

### Answer by username_4 on 2020-01-30. Score: 0

Apparently not! From Space.com's [Here's Why Saturn's Inner Moons Are Shaped Like Ravioli and Potatoes](https://www.space.com/40653-saturns-weird-moon-shapes-explained.html)

> The odd shapes of Saturn's inner moons, which resemble objects ranging from ravioli to potatoes, may be due to mergers of tiny moonlets, a new study finds.
>
> The new finding may help to explain how moons in general may form, researchers said in a new paper describing the work.

The paper in 21-May-2018 Nature Astronomy is [The peculiar shapes of Saturn’s small inner moons as evidence of mergers of similar-sized moonlets](https://www.nature.com/articles/s41550-018-0471-7) ([arXiv](https://arxiv.org/abs/1805.08682), [slideshare](https://www.slideshare.net/sacani/the-peculiar-shapes-of-saturns-small-inner-moons-as-evidence-of-mergers-of-similarsized-moonlets)) so **these are definitely considered to be non-spherical moons** made from mergers of "moonlets".

[![enter image description here](https://i.sstatic.net/H0azO.jpg)](https://i.sstatic.net/H0azO.jpg)

More (cropped) images of Pan from the NASA News item [Cassini Reveals Strange Shape of Saturn's Moon Pan](https://solarsystem.nasa.gov/news/13005/cassini-reveals-strange-shape-of-saturns-moon-pan/)

[![enter image description here](https://i.sstatic.net/JT0AE.png)](https://i.sstatic.net/JT0AE.png) [![enter image description here](https://i.sstatic.net/1J0tI.png)](https://i.sstatic.net/1J0tI.png)

> **Comments:**
> **username_0**: The question is whether they should fall into the same category. I gonna adjust my question.  
> **username_4**: @username_0 you have two answers now, it is strongly discouraged to change the question once people take the time to post answers. These **are considered moons** by astronomers, period. Also, a "should they" question solicits answers that are primarily opinion-based and therefore not appropriate for Stack Exchange. Instead of changing this question which would probably result in it being rolled back anyway, why not ask a follow-up question. You can link back here for background, and ask something like "Why...?"  
> **username_0**: Too late, sorry. But I don't think it's the end of the world if I change "spherical" to "differentiated".  
> **username_4**: @username_0 no it's not too late, I've rolled back. Seriously you should not change a question like that once answers have been posted. That's not how the site operates. The best way is to move forward and ask a new question about differentiated satellites and link back here. Next time you'll be more careful and write the question that you want answered the first time.  
> **username_0**: I don't need to post it again for I've wrote that Phobos and Ganymede being in the same category is weird. One should conclude that I ain't speaking of tiny spherical moonlets but of planetary-mass moons. It is obvious. May I change the text of the question (not the question itself) to add "differentiated"?  
> **username_4**: @username_0 I'm not a moderator, anyone with 10k reputation can edit and/or roll back anyone else's posts. I just wanted to let you know that there's no such thing as "too late." The text of the question is also the question itself (this isn't Quroa) so we shouldn't change one so that it doesn't match the other. I won't edit further but I'll mention again that asking "should" can get your question closed as looking for answers that are primarily opinion-based *as also mentioned* in the first comment under your question.  
> **username_0**: I meant that I've too late seen your advice not to change my question. The question also is whether there's a distinction between spherical differentiated moons and irregular satellites.  
> **username_4**: @username_0 okay go for it  

---

