Naked-Eye Observations of Jupiter’s Moons?

[Treeden]

I was looking at Jupiter last night through my bins and I could see Callisto above and to the right, and I could also see two of the remaining three moons below and to the left. It might have been all three on the lower side that I saw, but the image through my bins was not steady enough to be sure.

Jupiter was so bright last night that I couldn't see any of the moons with the naked eye, but a strange thing happened a little later when I went back inside. I have a large window in the kitchen that faces East and I often switch all my downstairs lights off and have a look skywards to get a general idea of the seeing. Well, I decided to have a final look at Jupiter as it was looking so splendid, and I was sure I could see Callisto too!

I was lucky to have a good level of darkness around my house last night, the sky was clear in patches and the seeing was reasonable to good at the time. I was looking through a double-glazed window with no visual aids other than my normal spectacles, and it really did look like Callisto. I also moved around to make sure it wasn't something on the glass of the window.

It made me think.... is it actually possible to observe Jupiter's moons with the naked eye? Has anyone here ever done it?

I found this article that sems to suggest it might be possible, but although my eyesight is not great, I am wondering if the conbination of my spectacles and the double-glazed window may have diffused Jupiter's glow sufficiently for this sighting of Callisto to be possible?

Does anyone have any experience of this, or any ideas that might explain it?

Thanks

Rob

[jimmyjamjoejoe]

More likely to be internal reflections in the glass tbh, you'd need to be very skilled at looking (it is actually something you learn lol), AND be blessed with amazing visual acuity. And even then, you really would be struggling from inside a house looking through a window.

[Treeden]

I checked the window to make sure it wasn't a mark or any kind of reflection. There did seem to be a small amount of diffusion though, so maybe that had something to do with it? Maybe I was seeing something that was in line with where Callisto was when I had looked earlier?

I would be interested to hear about some of the things others here have seen (or thought they had seen) with the naked eye? Especially things you didn't expect to be able to see?

[MAN or ASTROMAN]

This topic was discussed the other night on the latest S@N- none of the panel admitted to this feat of visual accuity,though that's not to say that it mightn't be possible.Having said that,if the overall brightness of Jupiter didn't blot out a naked eye view of the moons,then how come they weren't discovered until Galileo turned his telescope towards them? I think that the Arab astronomers or maybe the Chinese annals might have mentioned them had pre-telescopic views been possible.Just a few random thoughts.

[Capricorn]

Suppose the answer to this is: No you cannot.

Otherwise Galileo wouldn't have needed that scope of his to have discovered them, and he had a lot less light pollution then we have now so they would have stood out more. There have also been the Greeks, Romans, Egyptians, Babylonians, Mayans and many others that have studied the skies and no record or mention from any of them either.

My eyes have enough problems when they are looking down a scope.

[amansingh]

Folks it is definitely possible to see at least one moon of Jupiter with the naked eye.
 
I have been looking at Jupiter for the last 4 - 5 years off and on after having seen its moons for the first time in my Nikon 8X40 binoculars. But for the first time in so many years I saw one of Jupiter's moons extremely clearly about one week ago. At first I thought it must be a star but after several hours it was still in approx the same relative location to Jupiter. I have since seen it every night and also shown it to my wife (who was also able to see it clearly). The same has been confirmed with the Celestron 15X70 binoculars also. Every night the moon is coming "closer" to Jupiter (from a viewing standpoint) and I guess for the next 3 - 4 days it may not be visible at all as it may be either directly in front or directly behind Jupiter. For those who are interested I was able to see the moon at around 2 o'clock / 3 o'clock position wrt Jupiter while Jupiter was still towards the East and almost halfway to the zenith.
 
It is a very wonderful feeling. My guess is that the naked-eye observation could be due to:
1. Jupiter in opposition to Earth at this time?
2. Very clear and relatively dark skies at this time in Bangalore
3. Is it possible that the moon is not just bright due to the sun light but that Jupiter's reflected light is also catching favorably it in this position?

[amansingh]

Please note that I am at Bangalore and the elliptical passes through close to the zenith!

[acey]

Jupiter is currently extremely close to the 3.5 mag star Delta Geminorum (Wasat) and has been for the last couple of months. Any suspected naked-eye sighting of a Jovian moon during this period is most likely attributable to that star. It is certainly possible to see the moons with naked-eye, but all authenticated sightings that I know of have been done by obscuring the planet itself, e.g. with an intervening roof edge or tree. The moons are a bit fainter than 5th mag.

[amansingh]

Agree with Acey!

Does anyone know the maximum angular separation between Jupiter and it's farthest moons (out of the 4 usual suspects)? Is it around 10 arc minutes?

[Stu]

Looks like it is Callisto at just over 10 arc minutes separation at its maximum and currently mag 6.0. Next best opportunity looks to be around 22nd December.

Stu

[Paul M]

I've read a number of accounts (over the years) of people who can see the phases of Venus and the visual elongation (rings) of Saturn but don't recall any claims of visuals of the Jovian Satellites. 

I'm no visual athlete, far from it, so have nothing to offer from experience but I really wouldn't be surprised if they can be seen be a lucky few.

Many millions of years ago I worked in joinery manufacture. Double glazing wasn't my thing but I bought my last factory unit off a double glazing firm that was relocating. They needed more space for the equipment that they'd be needing to manufacture the latest whizz-bang BS/CE compliant double glazing units.

Apparently the glass is polymer/plastic coated to give it certain thermal and transmission properties.

I do wonder if the latest whizz-bang polar bear friendly glazing might have some (desirable?) optical qualities. Maybe some one who is just on the edge of spotting the Jovian Moons visually might just get the required boost from the glazing? Filtering glare, perhaps?

Just an Idea.

Sorry for waffling...again  

[Stu]

A while back I was out walking on the Heath, in the morning I think but can't really remember. Actually it must have been the early morning; being half asleep is the only reasonable excuse I have for the following. I saw a bright planet in the morning twilight, with a small star next to it. My addled brain put two and two together and made five. Of course, it 'must' be Jupiter with one of the Gallilean moons visible. Amazing I thought, and was happy in my ignorance until I checked later to see that it was obviously Venus passing close to a background star!

DOH!!!

Stu

[chiltonstar]

A while back I was out walking on the Heath, in the morning I think but can't really remember. Actually it must have been the early morning; being half asleep is the only reasonable excuse I have for the following. I saw a bright planet in the morning twilight, with a small star next to it. My addled brain put two and two together and made five. Of course, it 'must' be Jupiter with one of the Gallilean moons visible. Amazing I thought, and was happy in my ignorance until I checked later to see that it was obviously Venus passing close to a background star!

DOH!!!

Stu

Yes, same experience with Jupiter and a nearby star. I checked on Stellarium to confirm it, and then went outside again to see if I really could see the moons, in the orientation indicated by Stellarium. No luck, so I moved to a position where an overhead cable was just obscuring Jupiter - still no luck.

I have a feeling I tried the same thing 20 odd years ago when the Mk 1s were in better nick, with the same result.....no moons!

Chris

[alan potts]

I would have thought it was impossible to see any of Juptiers moons with the naked eye for the same reason Sirius is so difficult to split.

Alan

[chiltonstar]

I would have thought it was impossible to see any of Juptiers moons with the naked eye for the same reason Sirius is so difficult to split.

Alan

Maybe not impossible; Sirius and the Pup are 10 mags different in brightness, whereas for Jupiter and say Ganymede there is a 7.5 mag difference I think. The angular separation is a lot greater too between Jupiter and the moons.............

Chris

[Paul M]

Here is an interesting article:

http://denisdutton.com/jupiter_moons.htm

[entropia]

Jupiter is currently extremely close to the 3.5 mag star Delta Geminorum (Wasat) and has been for the last couple of months. Any suspected naked-eye sighting of a Jovian moon during this period is most likely attributable to that star. It is certainly possible to see the moons with naked-eye, but all authenticated sightings that I know of have been done by obscuring the planet itself, e.g. with an intervening roof edge or tree. The moons are a bit fainter than 5th mag.

 I was trying to look at Jupiter last night and while I was searching  through the finderscope I saw a star underneath Jupiter (checking my phone app it seems it was Wasat).  After a couple of hours, I came back and I was looking at Jupiter without a telescope. I though that I could see one of the moons but then I remembered it was the star I saw before

[ronin]

To me the problem is that there have been many civilisations with a serious interest of observing the sky and no light pollution, and I mean no "light pollution". Yet it took Galileo with a basic telescope to see Jupiter and it's moons as we know them to be.

We are by no means the first lot to take an interest in the sky and really our interest is less serious to us then it was to earlier people and civilisations. So I think there would have been many reports of the moons of Jupiter over the last 3-4000 years had they been visible by the naked eye. Our constellations are generally Greek and the stars are usually Arabic in name, these civilisations took a serious interest in the skies. The Chinese have a long history of astronomical observations easily covering 4000 years.

I would half believe that a person now seeing something near Jupiter will say it is a moon, because we now know there are moons, so by inference something close to Jupiter becomes a Jovian moon if it is or not.

Seeing Jupiters moons by eye sounds good but I have read at last count 4 posts on forums where someone has said they cannot find the moon. So I hold little hope of others seeing the Jovian moons by eye.

[Paul73]

I'm not sure that the "Galelio didn't spot 'em" argument is too safe.

When he wrote about the moons he was an academic in his mid 40's without access to modern light when studying. So it is fair to assume that his eyes had taken a bit of abuse and, that without the services of the fine people at Spacsavers (or similar), 20:20 vision would be unlikely.

Separation and glare from Jupiter would be a more likely impairment to spotting them unaided.

Paul