<p>@JamesK <a href="https://astronomy.stackexchange.com/a/23482/7982">nailed it</a>, I'll just add a little more.</p>

<p>Starting from <a href="http://lnfm1.sai.msu.ru/neb/nss/nsszph517he.htm" rel="noreferrer">the link</a> in that answer, I've found the figures below on <a href="http://lnfm1.sai.msu.ru/neb/nss/expl517.htm" rel="noreferrer">this page</a>. It looks like this cycle will be difficult to watch in the first months of 2021, until Jupiter moves far enough away from the Sun as seen from Earth. Also, the southern declination will make it more difficult to watch from the highest northern latitudes. </p>

<hr>

<blockquote>
  <p><strong>Parameters of the Earth-Sun-Jupiter configuration 
  during the mutual occultations and eclipses of the Galilean satellites in 2021</strong>. </p>
  
  <p><strong>The number of events per week (Monday to Sunday)</strong>. 
  Note: Only 30 % of the events can be seen on one observatory. 
  Note: Events before 3 March 2021 are not observable (Twilight). </p>
  
  <p><a href="https://i.sstatic.net/Z7fru.png" rel="noreferrer"><img src="https://i.sstatic.net/Z7fru.png" alt="enter image description here"></a></p>
  
  <p>Planetocentric planetoequatorial latitudes (deg) of the Earth and the Sun. </p>
  
  <p><a href="https://i.sstatic.net/2D0SA.png" rel="noreferrer"><img src="https://i.sstatic.net/2D0SA.png" alt="enter image description here"></a></p>
  
  <p>Geocentric angular distance (deg) between Jupiter and the Sun. </p>
  
  <p><a href="https://i.sstatic.net/5gigf.png" rel="noreferrer"><img src="https://i.sstatic.net/5gigf.png" alt="enter image description here"></a></p>
  
  <p>Declination of Jupiter (deg). </p>
  
  <p><a href="https://i.sstatic.net/PfUeS.png" rel="noreferrer"><img src="https://i.sstatic.net/PfUeS.png" alt="enter image description here"></a></p>
  
  <p>The Sun-Earth phase angle on Jupiter (deg). </p>
  
  <p><a href="https://i.sstatic.net/ddrX5.png" rel="noreferrer"><img src="https://i.sstatic.net/ddrX5.png" alt="enter image description here"></a></p>
</blockquote>

CC BY-SA 3.0
2017-11-11T08:58:13.473Z
2017-11-11T08:58:13.473Z
uhoh
<p>Mutual eclipses and occulations of Jupiter's moons occur during Jovian Equinox, twice in each orbit of Jupiter, and so roughly every 5.9 years.</p>
<p>The last two series of events were in 2015 and 2021 (there was a series of events between January and August <a href="http://lnfm1.sai.msu.ru/neb/nss/nsszph517he.htm" rel="nofollow noreferrer">http://lnfm1.sai.msu.ru/neb/nss/nsszph517he.htm</a>), so the next will start sometime around late 2026 or 2027.</p>

CC BY-SA 3.0
2017-11-11T08:06:53.630Z
Thanks! That will make a nice 70th birthday treat for me. :-)
Mick
CC BY-SA 3.0
2017-11-11T08:32:09.537Z
Excellent! Using the geocentric default (500) it looks like after August 30, there's one more straggler on November 16. Also thanks for mentioning that there will also be mutual occultations - the two moons would be unresolved in a small telescope, but the light contribution from the one behind would suddenly be removed from the line-of-sight.
uhoh
CC BY-SA 3.0
2017-11-18T12:44:18.513Z
Oh, and happy birthday in advance to @Mick!
uhoh
CC BY-SA 4.0
2017-11-11T08:02:58.107Z
2023-09-10T08:45:57.103Z
2023-09-10T08:45:57.103Z
James K
<p>When I was young (I won't tell you when) I saw one of the four <a href="https://en.wikipedia.org/wiki/Galilean_moons" rel="noreferrer">Galilean moons</a> of Jupiter suddenly disappear while watching through a small refractor. It wasn't a coincidence, I'd seen the prediction in some announcements in Sky and Telescope and it happened like clockwork. The orbital plane of the Galilean moons had rotated so that it included the Sun, and the moons were Eclipsing each other, or so I remember.</p>

<p>Will this happen again? If so, when will they start, and where can I find predictions of individual eclipses?</p>

CC BY-SA 3.0
2017-11-11T03:40:04.680Z
Related: [Eclipses of Jupiter's Moon during Retrograde motion](https://astronomy.stackexchange.com/q/12042/7982).
uhoh
CC BY-SA 3.0
2017-11-11T05:18:23.793Z
This is a really interesting question. Perhaps, not of much interest to professional astronomers, but an answer might encourage me to get my telescope out again.
Mick
CC BY-SA 4.0
2019-02-20T00:09:15.230Z
@Mick only two more years to go now! ;-)
uhoh
CC BY-SA 4.0
2019-02-20T00:50:08.190Z
Thanks for the reminder. I'd better get busy and finish my 8" scope, otherwise I'll have to use my 4" (although it shows Jupiter nicely enough). I'l be 70 when it happens. Gah!
Mick
CC BY-SA 4.0
2019-02-20T01:04:17.750Z
@Mick if you are anything like I am, two years *might be* enough time to find something. I saw one mutual occultation decades ago, sometime in the 1980's. It's there, it's not there, then it's there again. As long as it's not too close to Jupiter at the time, I don't think the larger aperture helps particularly much. *But don't let that be an excuse not to start looking!* ;-)
uhoh
CC BY-SA 4.0
2020-10-05T11:15:14.297Z
@Mick how's the 8" scope?
uhoh
CC BY-SA 4.0
2020-10-05T11:25:36.010Z
Oh, dear! The 4" scope is up the attic, gathering dust. I haven't used it for years. The 8" mirror is still half-finished. I doubt if I will ever complete it. Maybe I'll get the 4" down and take a look at Mars while it's nicely placed. I did have a decent squint at NEOWISE with my binocs, but the weather closed in, so I didn't bother with the scope. Thanks for asking.
Mick
CC BY-SA 4.0
2020-10-05T12:26:56.907Z
@Mick lucky for you on NEOWISE, combination of cloudy evenings and schedule prevented me from getting somewhere where I'd have a reasonably dark sky. We'll there's always going to be another comet.
uhoh
<jupiter><natural-satellites><eclipse-non-earth-related>
When will the next series of mutual eclipses of Jupiter's moons begin?
uhoh
# When will the next series of mutual eclipses of Jupiter's moons begin?

(Asked by: username_0 on 2017-11-11)

When I was young (I won't tell you when) I saw one of the four [Galilean moons](https://en.wikipedia.org/wiki/Galilean_moons) of Jupiter suddenly disappear while watching through a small refractor. It wasn't a coincidence, I'd seen the prediction in some announcements in Sky and Telescope and it happened like clockwork. The orbital plane of the Galilean moons had rotated so that it included the Sun, and the moons were Eclipsing each other, or so I remember.

Will this happen again? If so, when will they start, and where can I find predictions of individual eclipses?

**Tags:** jupiter, natural-satellites, eclipse-non-earth-related

> **Comments:**
> **username_0**: Related: [Eclipses of Jupiter's Moon during Retrograde motion](https://astronomy.stackexchange.com/q/12042/7982).  
> **username_1**: This is a really interesting question. Perhaps, not of much interest to professional astronomers, but an answer might encourage me to get my telescope out again.  
> **username_0**: @username_1 only two more years to go now! ;-)  
> **username_1**: Thanks for the reminder. I'd better get busy and finish my 8" scope, otherwise I'll have to use my 4" (although it shows Jupiter nicely enough). I'l be 70 when it happens. Gah!  
> **username_0**: @username_1 if you are anything like I am, two years *might be* enough time to find something. I saw one mutual occultation decades ago, sometime in the 1980's. It's there, it's not there, then it's there again. As long as it's not too close to Jupiter at the time, I don't think the larger aperture helps particularly much. *But don't let that be an excuse not to start looking!* ;-)  
> **username_0**: @username_1 how's the 8" scope?  
> **username_1**: Oh, dear! The 4" scope is up the attic, gathering dust. I haven't used it for years. The 8" mirror is still half-finished. I doubt if I will ever complete it. Maybe I'll get the 4" down and take a look at Mars while it's nicely placed. I did have a decent squint at NEOWISE with my binocs, but the weather closed in, so I didn't bother with the scope. Thanks for asking.  
> **username_0**: @username_1 lucky for you on NEOWISE, combination of cloudy evenings and schedule prevented me from getting somewhere where I'd have a reasonably dark sky. We'll there's always going to be another comet.  

---

## 2 answers

### Answer by username_2 on 2017-11-11. Score: 7 | Accepted answer

Mutual eclipses and occulations of Jupiter's moons occur during Jovian Equinox, twice in each orbit of Jupiter, and so roughly every 5.9 years.

The last two series of events were in 2015 and 2021 (there was a series of events between January and August <http://lnfm1.sai.msu.ru/neb/nss/nsszph517he.htm>), so the next will start sometime around late 2026 or 2027.

> **Comments:**
> **username_1**: Thanks! That will make a nice 70th birthday treat for me. :-)  
> **username_0**: Excellent! Using the geocentric default (500) it looks like after August 30, there's one more straggler on November 16. Also thanks for mentioning that there will also be mutual occultations - the two moons would be unresolved in a small telescope, but the light contribution from the one behind would suddenly be removed from the line-of-sight.  
> **username_0**: Oh, and happy birthday in advance to @username_1!  

---

### Answer by username_0 on 2017-11-11. Score: 5

@JamesK [nailed it](https://astronomy.stackexchange.com/a/23482/7982), I'll just add a little more.

Starting from [the link](http://lnfm1.sai.msu.ru/neb/nss/nsszph517he.htm) in that answer, I've found the figures below on [this page](http://lnfm1.sai.msu.ru/neb/nss/expl517.htm). It looks like this cycle will be difficult to watch in the first months of 2021, until Jupiter moves far enough away from the Sun as seen from Earth. Also, the southern declination will make it more difficult to watch from the highest northern latitudes.

---

> **Parameters of the Earth-Sun-Jupiter configuration
> during the mutual occultations and eclipses of the Galilean satellites in 2021**.
>
> **The number of events per week (Monday to Sunday)**.
> Note: Only 30 % of the events can be seen on one observatory.
> Note: Events before 3 March 2021 are not observable (Twilight).
>
> [![enter image description here](https://i.sstatic.net/Z7fru.png)](https://i.sstatic.net/Z7fru.png)
>
> Planetocentric planetoequatorial latitudes (deg) of the Earth and the Sun.
>
> [![enter image description here](https://i.sstatic.net/2D0SA.png)](https://i.sstatic.net/2D0SA.png)
>
> Geocentric angular distance (deg) between Jupiter and the Sun.
>
> [![enter image description here](https://i.sstatic.net/5gigf.png)](https://i.sstatic.net/5gigf.png)
>
> Declination of Jupiter (deg).
>
> [![enter image description here](https://i.sstatic.net/PfUeS.png)](https://i.sstatic.net/PfUeS.png)
>
> The Sun-Earth phase angle on Jupiter (deg).
>
> [![enter image description here](https://i.sstatic.net/ddrX5.png)](https://i.sstatic.net/ddrX5.png)


---

