<p>The orbital inclination of Europa is <a href="https://en.wikipedia.org/wiki/Europa_(moon)" rel="nofollow noreferrer"><span class="math-container">$0.470^{\circ}$</span></a>, so it is safe to ignore this inclination. Also, Jupiter has a axial tilt of <span class="math-container">$3.13^{\circ}$</span>.</p>
<p>The mean orbital radius of Europa is <span class="math-container">$670,900 $</span>km and the radius of Jupiter is <span class="math-container">$69,911$</span>km, that means observed on Europa, the apparent diameter of Jupiter is <span class="math-container">$12^{\circ}$</span>,(it is just trig function). Way bigger than the Sun apparent diameter observed in Jupiter (in context, the apparent solar diameter observed on Earth is around <span class="math-container">$0.5^{\circ}$</span>).</p>
<p>This means that Jupiter can cover the entire Sun's disk. Also the <em>Europan latitude</em> (compare to declination of Equatorial system) of Sun will not exceed a maximum of <span class="math-container">$\pm 4^{\circ}$</span> while Jupiter is always on the <em>Europan Equator</em> (compare to celestial equator of Equatorial system).</p>
<p>In conclusion, everywhere on Europa can see Jupiter eclipsing the Sun, location does not matter here, only day/night matter, you can choose whatever location you prefer and use it in your story.</p>
<p>This may also be interesting: <a href="https://en.wikipedia.org/wiki/Libration" rel="nofollow noreferrer">libration</a></p>

CC BY-SA 4.0
2024-07-24T12:19:27.657Z
Thank you! Just a correction. As far as I have read until now, Europa is tidally locked to Jupiter, like the Moon is to Earth. Then Jupiter can be observed from anywhere in the hemisphere permanently facing Jupiter but not from the other, which is permanently turned away, right?
Krišjānis Liepiņš
CC BY-SA 4.0
2024-07-24T12:21:58.250Z
Neglecting libration, what you are saying is correct. Considering this effect, places on the edge of the side facing Jupiter and close to north and south pole of Europa can also see Jupiter, but I doubt they can see an eclipse.
Polaris5744
CC BY-SA 4.0
2024-07-24T22:55:26.783Z
Also, you get an eclipse every night/month?
Paŭlo Ebermann
CC BY-SA 4.0
2024-07-25T01:42:55.760Z
that is correct
Polaris5744
CC BY-SA 4.0
2024-07-25T14:28:09.613Z
I know for a fact that there are plenty of places on our Moon that will **never** witness Earth eclipsing the sun, and those places are ... at the backside of our moon :-) I have no idea whether Europa has tidal locking around Jupiter, but if this were the case, all your calculations might be pointless :-)
Dominique
CC BY-SA 4.0
2024-07-26T07:35:54.010Z
@PaŭloEbermann That depends on how you define "night". As settlements would be buried into or below the moon's ice crust to protect people from radiation (observing the eclipse would be possible from special observation spots covered with a special dome), a day would most likely be close to Earth's day to which we're adapted to through evolution. Then, the eclipse would happen once every couple of days.
Krišjānis Liepiņš
CC BY-SA 4.0
2024-07-26T22:23:43.190Z
@KrišjānisLiepiņš I meant every rotation, i.e. every "day" for Europa, which is an "Europa-month" for Jupiter. ("Night" was a mistake by me.) (Modulo the difference due to Jupiter's rotation around the sun.)
Paŭlo Ebermann
CC BY-SA 4.0
2024-08-05T13:05:30.223Z
Europa DOES have tidal locking. So, from almost half of the moon's territory you will not see Jupiter at all. So, the part "everywhere in Europa" is not correct. -1
Heopps
CC BY-SA 4.0
2024-08-06T09:37:44.293Z
@Heopps, Did you read the comments……
Polaris5744
CC BY-SA 4.0
2024-08-06T10:58:01.153Z
@Polaris - ok, does "everywhere in Europa can see eclipsing the Sun" mean "everywhere on Jupiter-facing" hemisphere of Europa? If yes, it's not clear enough and can be misread. If "everywhere" means literally everywhere - I don't see how it can be right. Europa is tidally locked, so almost all the anti-Jupiter hemisphere doesn't see Jupiter and so we couldn't see it eclipsing the Sun. ("Almost all" the hemisphere because of the librations)
Heopps
CC BY-SA 4.0
2024-08-06T13:31:30.300Z
@Heopps, Look, if you didn't read the comments, it is not my problem, it is literally the first one.
Polaris5744
CC BY-SA 4.0
2024-08-06T13:36:48.540Z
@Heopps, why don't you edit the anwser instead of saying this or that is wrong? Action speaks louder than words (the correction is in the comments anyway)
Polaris5744
CC BY-SA 4.0
2024-07-24T12:07:09.803Z
2024-07-25T08:48:14.590Z
2024-07-25T08:48:14.590Z
Polaris5744
<p>== Just an addition to Polaris' excellent answer. The specific locations you ask about would see Jupiter nearer to the horizon in proportion to that location's angular distance from the (fixed) Europa terminator.</p>
<p>From the phase angle seen by this spacecraft, Conamara Chaos appears to be pretty near the terminator, so it would see Jupiter eclipse the sun near or on the horizon:</p>
<p><a href="https://i.sstatic.net/pJMUrvfg.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/pJMUrvfg.jpg" alt="Conamara Chaos" /></a></p>

CC BY-SA 4.0
2024-07-24T13:23:33.573Z
2024-07-24T13:23:33.573Z
Miss Understands
<p>I'm currently writing a story happening on Jupiter's moon Europa in the distant future and am looking for a location of the settlement where it takes place. As the protagonist likes to observe Jupiter eclipsing the sun before her workday, it should be a location from which it's possible to observe this occurrence.</p>
<p>I tried to browse WolframAlpha, Wikipedia and USGS databases, looking at coordinates and considering this location should be in the moon's hemisphere facing Jupiter and in the Western part of it so that Jupiter wouldn't be right overhead and blocking the entire sky (also it would be aesthetically much better view with Jupiter being close to the horizon). But I don't understand these coordinate systems.</p>
<p>I asked ChatGPT to brainstorm which features would fit, and tried to define the criteria as both &quot;the sun setting behind Jupiter&quot; and &quot;Jupiter eclipsing the sun&quot;. But that requires fact-checking.</p>
<p>Ideas ChatGPT offered:</p>
<ul>
<li>Conamara Chaos</li>
<li>Pwyll Crater</li>
<li>Thera Macula</li>
<li>Agenor Linea</li>
<li>Minos Linea</li>
<li>Katreus Linea</li>
</ul>
<p>So I have a two-fold question:</p>
<p>Which of these locations fits better? As a fact-checking: is any of these in the wrong location to observe Jupiter eclipsing the sun?</p>
<p>Which other location(s) would also fit the criteria, and maybe better than any of these?</p>

CC BY-SA 4.0
2024-07-24T11:25:13.323Z
Probably all of the locations, you can calculate the visibility based on the "latitude" of those locations and the orbital inclination of Europa.
Polaris5744
CC BY-SA 4.0
2024-07-24T11:41:48.793Z
@Polaris5744 I don't know how to calculate this.
Krišjānis Liepiņš
CC BY-SA 4.0
2024-07-24T11:43:14.307Z
Okay, give me some time and I will try my best to calculate this.
Polaris5744
<jupiter><surface><europa>
From which notable Europa's surface features could be possible to observe Jupiter eclipsing the sun?
Krišjānis Liepiņš
# From which notable Europa's surface features could be possible to observe Jupiter eclipsing the sun?

(Asked by: username_0 on 2024-07-24)

I'm currently writing a story happening on Jupiter's moon Europa in the distant future and am looking for a location of the settlement where it takes place. As the protagonist likes to observe Jupiter eclipsing the sun before her workday, it should be a location from which it's possible to observe this occurrence.

I tried to browse WolframAlpha, Wikipedia and USGS databases, looking at coordinates and considering this location should be in the moon's hemisphere facing Jupiter and in the Western part of it so that Jupiter wouldn't be right overhead and blocking the entire sky (also it would be aesthetically much better view with Jupiter being close to the horizon). But I don't understand these coordinate systems.

I asked ChatGPT to brainstorm which features would fit, and tried to define the criteria as both "the sun setting behind Jupiter" and "Jupiter eclipsing the sun". But that requires fact-checking.

Ideas ChatGPT offered:

* Conamara Chaos
* Pwyll Crater
* Thera Macula
* Agenor Linea
* Minos Linea
* Katreus Linea

So I have a two-fold question:

Which of these locations fits better? As a fact-checking: is any of these in the wrong location to observe Jupiter eclipsing the sun?

Which other location(s) would also fit the criteria, and maybe better than any of these?

**Tags:** jupiter, surface, europa
> **Comments:**
> **username_1**: Probably all of the locations, you can calculate the visibility based on the "latitude" of those locations and the orbital inclination of Europa.  
> **username_0**: @Polaris5744 I don't know how to calculate this.  
> **username_1**: Okay, give me some time and I will try my best to calculate this.  

---

## 2 answers

### Answer by username_1 on 2024-07-24. Score: 8

The orbital inclination of Europa is [$0.470^{\circ}$](https://en.wikipedia.org/wiki/Europa_(moon)), so it is safe to ignore this inclination. Also, Jupiter has a axial tilt of $3.13^{\circ}$.

The mean orbital radius of Europa is $670,900 $km and the radius of Jupiter is $69,911$km, that means observed on Europa, the apparent diameter of Jupiter is $12^{\circ}$,(it is just trig function). Way bigger than the Sun apparent diameter observed in Jupiter (in context, the apparent solar diameter observed on Earth is around $0.5^{\circ}$).

This means that Jupiter can cover the entire Sun's disk. Also the *Europan latitude* (compare to declination of Equatorial system) of Sun will not exceed a maximum of $\pm 4^{\circ}$ while Jupiter is always on the *Europan Equator* (compare to celestial equator of Equatorial system).

In conclusion, everywhere on Europa can see Jupiter eclipsing the Sun, location does not matter here, only day/night matter, you can choose whatever location you prefer and use it in your story.

This may also be interesting: [libration](https://en.wikipedia.org/wiki/Libration)

> **Comments:**
> **username_0**: Thank you! Just a correction. As far as I have read until now, Europa is tidally locked to Jupiter, like the Moon is to Earth. Then Jupiter can be observed from anywhere in the hemisphere permanently facing Jupiter but not from the other, which is permanently turned away, right?  
> **username_1**: Neglecting libration, what you are saying is correct. Considering this effect, places on the edge of the side facing Jupiter and close to north and south pole of Europa can also see Jupiter, but I doubt they can see an eclipse.  
> **username_2**: Also, you get an eclipse every night/month?  
> **username_1**: that is correct  
> **username_3**: I know for a fact that there are plenty of places on our Moon that will **never** witness Earth eclipsing the sun, and those places are ... at the backside of our moon :-) I have no idea whether Europa has tidal locking around Jupiter, but if this were the case, all your calculations might be pointless :-)  
> **username_0**: @PaŭloEbermann That depends on how you define "night". As settlements would be buried into or below the moon's ice crust to protect people from radiation (observing the eclipse would be possible from special observation spots covered with a special dome), a day would most likely be close to Earth's day to which we're adapted to through evolution. Then, the eclipse would happen once every couple of days.  
> **username_2**: @KrišjānisLiepiņš I meant every rotation, i.e. every "day" for Europa, which is an "Europa-month" for Jupiter. ("Night" was a mistake by me.) (Modulo the difference due to Jupiter's rotation around the sun.)  
> **username_4**: Europa DOES have tidal locking. So, from almost half of the moon's territory you will not see Jupiter at all. So, the part "everywhere in Europa" is not correct. -1  
> **username_1**: @Heopps, Did you read the comments……  
> **username_4**: @Polaris - ok, does "everywhere in Europa can see eclipsing the Sun" mean "everywhere on Jupiter-facing" hemisphere of Europa? If yes, it's not clear enough and can be misread. If "everywhere" means literally everywhere - I don't see how it can be right. Europa is tidally locked, so almost all the anti-Jupiter hemisphere doesn't see Jupiter and so we couldn't see it eclipsing the Sun. ("Almost all" the hemisphere because of the librations)  
> **username_1**: @Heopps, Look, if you didn't read the comments, it is not my problem, it is literally the first one.  
> **username_1**: @Heopps, why don't you edit the anwser instead of saying this or that is wrong? Action speaks louder than words (the correction is in the comments anyway)  

---

### Answer by username_5 on 2024-07-24. Score: 3

== Just an addition to Polaris' excellent answer. The specific locations you ask about would see Jupiter nearer to the horizon in proportion to that location's angular distance from the (fixed) Europa terminator.

From the phase angle seen by this spacecraft, Conamara Chaos appears to be pretty near the terminator, so it would see Jupiter eclipse the sun near or on the horizon:

[![Conamara Chaos](https://i.sstatic.net/pJMUrvfg.jpg)](https://i.sstatic.net/pJMUrvfg.jpg)


---

