Today we are going to be taking a look at Jupiter in the morning. Specifically we’re going to be looking at some of Jupiter’s largest moons, the Galilean moons, and how they occult each other or have conjunctions with each other over the course of October. That premise may sound familiar to some of you, that may sound like deja vu, because we took a look at these moons and how they occult each other over the course of September last month. This time we’re going to be looking at them over the course of October
From here in Ireland, I don’t know if we’ll get to see any. On the 3rd we get very close to seeing an occultation of Io by Ganymede, almost, just before they slip behind Jupiter. Thankfully a commenter was nice enough to list out some of the occultations and where they will be visible from. It is the same commenter who listed out these events for the previous video in September. So, again, this is an open invitation to anyone who knows of some events in the sky, just let me if you would like to see a particular event discussed by commenting here or on YouTube.
To begin with, we are starting on the 1st of October and we are going to go to Adamstown. All of the locations we will look from are cities or towns, capitals or at least capitals of territories or dependencies. Adamstown is the capital of the Pitcairn Islands, which are over in the Pacific and this is the location I was told to look from. We’ve come all the way back to just sunset, Saturn is just after rising there in the east, so we have to come all the way through to sunrise before we see first Mars and then Jupiter. We’ll zoom in on Jupiter and take a closer look. Of course, the conjunctions and occultations of these moons can be very brief, but it looks like we’re already close to one, with Io and Europa being quite close together. We will focus on the two of those and we’ll move through a little bit of time to see if we can get them closer together. As we get closer here, we can see the number of air masses decreasing in Stellarium, which means these objects are getting higher in the sky and that also means we’re getting closer to sunrise. Just before it gets bright, a little bit of Io gets blocked by Europa.
That is only a partial occultation. We’re going to move forward to the third. Changing the date is enough to bring us very close to sunrise, so we will pull back a little bit earlier to get back into darkness. Zooming in on Io and Ganymede, they’re already very close together. Let’s see if we can get them closer, and we can. They have a very clear occultation, a large portion of Ganymede is being blocked out by Io. Again, this is from Adamstown in the Pitcairn Islands, just like on the first one with Io and Europa, but this one on the 3rd of October is a much more obvious occultation. At least, it’s much easier for us to see in Stellarium, with all of the benefits of simulation. Using an incredibly large telescope, with all of the oculars and lenses that we can pull out to help ourselves, and it doesn’t look like we can resolve these moons to anything more than bright blobs. However, by watching them over a significant period of time, you would be able to see two moons seem to fuse into one, even though the details that are visible in simulation are not going to be visible through most telescopes. Any telescope that you can just buy in a shop won’t show the same level of detail.
We do still have some more areas to check out, so we will zoom back out and head to the opposite side of the Americas, to Jamestown in St. Helena, which is an island in the middle of the Atlantic. It is closer to Africa than it is to South America here, but it is more or less in the middle of the Atlantic. St. Helena is one of the islands in the same island group, along the same ridge, as Ascension Island and Tristan da Cunha. Still looking at morning time, we have Jupiter in darkness. We are moving ahead to the 5th, when the Moon and Mars have that conjunction, which we will be able to see from here in Ireland. Zooming in a little bit closer on the Jovian system, and it looks like Io and Callisto are pretty much right on top of each other, and indeed Callisto passes in front of Io. Again, it’s not a total occultation, and very similar to the last one that we took a look at, through most telescopes you would see two distinct moons appearing to fuse into one, but you wouldn’t be able to see the level of detail provided by Stellarium, where we can see all of the cracks and craters on Callisto and the volcanoes on the surface of Io. That one is the 5th of October from Jamestown on St Helena in the Atlantic Ocean.
We’re going to move ahead just one day, which brings the Moon very close to Jupiter, but we are also going to change our location from the Atlantic to the Caribbean. We’re not going too far here, well, we are moving a pretty significant distance, but we’re just not crossing any continents to do so. We’re going to Gustavia in the Caribbean, the capital of Saint Barthelemy, which is a collectivity of France. The Moon and Jupiter get really close together on this date, so there’s definitely a conjunction of the Moon and Jupiter. However, the peak of that conjunction is not the right time for the moons to move past each other. We need to move back a little bit to see Io and Callisto, with Io getting completely occulted by Callisto. This is a proper occultation, a full total occultation of Io by Callisto, on the same morning, on the same date as the conjunction between Jupiter and our Moon. So there is plenty to see around sunrise on this date, at least if you are in the Caribbean. The Moon and Jupiter won’t be visible so close together for us. On Saint Barthélemy, we’re at UTC -4 looking at 5 o’clock in the morning. For us, that’s 10 o’clock, so Jupiter wouldn’t be visible for us here in Ireland on the 6th at this moment. However, it is a particularly nice view from the Caribbean. There is a good chance that the lunar occultation, the Moons of Jupiter, occulting each other will be visible from other areas in the Caribbean but the conjunction of our Moon and Jupiter certainly will.
Lastly for this piece, and of course we’re still only covering early October, we need to move forward one day to the 7th and to Tashkent, the capital of Uzbekistan. Even just one day forward, the Moon is now closer to the Sun than Jupiter, things have shifted in the sky. If we zoom into Jupiter here, it looks like Europa and Ganymede are the two more close together moons. In the background of these events, various little moons such as Thebe, Metis and Amalthea have no doubt been occulted and transited, but they would be even more difficult to see. Easier to see is the pretty clear partial occultation of Europa by Ganymede. Ganymede blocks out most of Europa. Moving at real time, there is some noticeable movement of Europa with relation to Ganymede. These moons are orbiting Jupiter versus very quickly, if you had a telescope big enough, you would be able to see that movement happening in real time. Unfortunately, you would need an incredibly big telescope. Nothing that Stellarium simulates is big enough.
I hope that you get to see some of these occultations and conjunctions. If you are lucky enough to live in the locations that I’ve listed here, you now know a few of the dates when you will be able to see see them. Later in the month, in a couple of pieces time, we will take a look at some more of these Galilean occultations and conjunctions that are happening later in the month from other locations. Until then, I hope that you enjoyed this piece. If you did, please do like it and if you like this kind of content, please subscribe to this website and my YouTube channel. Most importantly, thank you very much for reading and hopefully I’ll see you back here next time.
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