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Can you see detail on Jupiters Moons?

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#1 HotRod217

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Posted 07 May 2021 - 01:33 PM

Would it theoretically be possible to see any detail on moons in our solar system? 


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#2 spereira

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Posted 07 May 2021 - 01:34 PM

Moving to Solar System Observing.

 

smp



#3 sharkmelley

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Posted 07 May 2021 - 02:08 PM

Yes, an 11" or 14" SCT or Newtonian will give some detail on Ganymede, for instance.

 

Mark


Edited by sharkmelley, 07 May 2021 - 02:10 PM.

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#4 Fossil Light

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Posted 07 May 2021 - 02:21 PM

Not sure about visually but you can image detail on the Galilean moons without too much difficulty provided you have enough resolving power.

 

Have a look at these for instance;

 

https://skyinspector...piter/#bwg5/193

https://skyinspector...piter/#bwg5/202

https://skyinspector...ive-2/#bwg8/365

https://skyinspector...ive-2/#bwg8/338



#5 gene 4181

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Posted 07 May 2021 - 02:47 PM

 I've seen  albedo features and color  just as    a moon came  off the disc after transiting  a "few" times.  Its not a regular occurrence though, more seeing dependent I'd guess.  


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#6 Quinnipiac Monster

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Posted 10 May 2021 - 07:47 AM

No albedo features, I guess that would take really great seeing and/or very high powers, like on Mars when it's very small (I used up to 700x with a 10" lately). I never tried seriously though. However, I remember the orangish tint of Titan being very obvious when I parked the planet outside the field of view of the eyepiece.



#7 dave253

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Posted 10 May 2021 - 11:42 AM

I’ve seen the Jovian moons as clear disks maybe twice in five years. (14” F5) The seeing needs to be excellent, which is rare here. When those conditions arrived, I was busy looking at the planet. Hopefully this winter will be good. 



#8 maroubra_boy

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Posted 12 May 2021 - 01:33 AM

Over the last few years Jupiter has been going over us here in Australia close to zenith.

With my 9" Santel Mak it has been very easy to not only resolve the Galilean moons as wee disks, but also detect tonal/albedo markings. Also hue and value differences between them. These are mostly while they are transiting across Jupiter's disk as this reduces the huge contrast between the moons & the black of space.

The size difference between the Moons' disks is also noticeable.

As for actual features, I thought I could see some details on Ganymede one time, but the vision was fleeting due to seeing, so I cannot confirm more than "I thought".

Shall be bashing Jupiter again this year...

Alex.
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#9 CHASLX200

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Posted 14 May 2021 - 07:05 PM

I can't say that i have seen real detail. I have used 11" to 18" high end Newts for years in my super steady seeing in FL.  Powers of 1150x are fine in 14.5" and bigger scopes. On my best nites i can get good size disk out of the moons and have seen shading on two of the moons.  Just got another 18" scope so i will be pushing it to the max and see what it can do.  So far it did super good at 400x this week with maybe 7 seeing. I could see lighter shading of pink inside the great red spot. Seeing was too choppy to push to 800x or more.



#10 luxo II

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Posted 17 May 2021 - 12:15 AM

My 10” APM has shown markings on Ganymede at 600-750X, that much is possible… tho there weren't many opportunities last year - the weather was mostly abysmal. With planet season shifting to our winter/spring it's going to be challenging, again.


Edited by luxo II, 17 May 2021 - 01:18 AM.

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#11 PlanetMacro

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Posted 02 July 2021 - 12:35 PM

Yes, you can see details on the moons of Jupiter and Saturn provided you have access to some of the worlds largest modern telescopes. You guys are mistaking floaters in your eyeballs for details. 


Edited by PlanetMacro, 02 July 2021 - 12:35 PM.


#12 maroubra_boy

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Posted 02 July 2021 - 04:53 PM

Yes, you can see details on the moons of Jupiter and Saturn provided you have access to some of the worlds largest modern telescopes. You guys are mistaking floaters in your eyeballs for details. 

Sorry mate, but these are the words said by someone who has not viewed them using a scope over 4".  Nice fracs there, but not the aperture to pull the details I have seen with a 9" Santel Mak.

 

Below is a sketch showing Ganymede by the French amateur astronomer Frederic Burgeot using a 16" Newt.  The pic appears in the publication "Planetary Astronomy".  This sketch is truly remarkable as an indicator of what can actually be observed detail wise.  No floaters here.

 

Alex.

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#13 Asbytec

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Posted 02 July 2021 - 05:37 PM

Yes, you can see details on the moons of Jupiter and Saturn provided you have access to some of the worlds largest modern telescopes. You guys are mistaking floaters in your eyeballs for details. 

Alex is right in his post above.

 

I know what floaters look like, believe me. However, it absolutely is possible to see "detail" on at least Ganymede. It does have a few high contrast features that can be seen when well placed facing the earth. If you have a keen eye, you might notice an apparent elongation to Io, too, especially relative to Europa's disc. This dashed appearance is often imaged against the Jovian atmosphere, but it's possible against the back of space, too. Some observers report detail on Callisto, but any detail would be lower contrast. I am not aware of any detail observed on Europa. 

 

It's important to remember, the Jovian moon's "discs" are not diffraction discs where no detail is possible. They are actually very small extended objects even in a modest 4 to 6" aperture. However, the detail is at very high spatial frequencies, so the detail must be of sufficient (read high) contrast transferred to the telescopic image. And of course, seeing must be very good, the scope must be thermally stable and well collimated, and the observe needs to pay attention. 

 

That the Jovian moons are not just colored discs should be common knowledge if it was not for "average seeing" conditions. Below is my best rendering of Ganymede on a very good evening through a 6" aperture when Jupiter was near the zenith in near perfect seeing and some features (and attempted identification) well placed. Also below are some threads on observing the Jovian moons. You can use JPL Sim to determine if any detail is possible on a given night for Ganymede.

 

Edit to add: I normally observe Jove at around 240x. At this magnification Ganymede looks like a "disc". So one can be forgiven for observing Ganymede as a very small "disc" not too different from the Airy disc of a bright star. That's what it looks like. I never thought to look closer, either. Never thought anything was possible because it is not well known common knowledge. I was proven wrong on the urging of a friend and by my own lying eyes at higher magnification in some of the best seeing I know of. The detail is incredibly small, of course it has to be to fit within the small disc.

 

Ganymede's disc is about the same diameter of the Airy disc (to the dark interspace) of a 6" aperture. However, the detail is "resolved" (not the Rayleigh meaning) on the focal plane by the aperture. A scope can resolve detail much smaller than the Airy disc so long as the image, itself, is not an Airy diffraction artifact. Ganymede's image is not a pure diffraction artifact. The problem is Ganymede is not well resolved on our eye at lower magnification. Higher magnification, not talking about empty magnification, helps give a more comfortable image scale for those of us with average acuity. 

 

ganymede.jpg

 

More often than not, Ganymede looks like below. 

 

Ganymede best.png

 

https://www.cloudyni...io#entry5901093

https://www.cloudyni...it-of-io/?hl=io

https://www.cloudyni...rvations/?hl=io


Edited by Asbytec, 03 July 2021 - 05:54 AM.

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#14 maroubra_boy

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Posted 26 July 2021 - 10:35 PM

I've just come across another sketch of Ganymede right here on CN.  CarlosEH posted the sketch he did on his gallery done on the 15th of November 2011 using a 9" Santel Mak.  So yeah, detail can be seen if your scope is good enough coupled with outstanding seeing conditions.

 

A little gem of a piece that was posted back in 2011 that answered the OP:

 

https://www.cloudyni...vember-15-2011/

 

 

gallery_7454_3770_1407449705_26271.jpg  

 

"A comparison of a visual observation of Ganymede (III) made on November 15, 2011 (01:45 U.T.) using my 9-inch (23-cm) F/13.5 Maksutov-Cassegrain. Galileo Regio and Marius Regio are separated by a bright Uruk Sulcus."  CarlosEH


Edited by maroubra_boy, 26 July 2021 - 10:35 PM.

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#15 smithrrlyr

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Posted 26 July 2021 - 10:55 PM

Harvard astronomer William Pickering (1858-1938) believed that he visually observed details on Jupiter's Galilean moons.  However, his interpretations of his observations were sometimes imaginative, to say the least.  He thought, for example, that the moons showed disks of significantly elliptical form.  See, for example, his Harvard Annals paper from 1937:

 

http://articles.adsa...AnHar..82...61P

 

Pickering is also known, as many readers are probably aware, for his belief that he saw evidence of life on the Earth's moon. He was a skillful but not a critical observer.



#16 Asbytec

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Posted 29 July 2021 - 09:09 AM

I've read the egg shaped moon article. Very enjoyable. Nevertheless, he is correct about detail being possible on the Jovian moons through a modest aperture. Several observers have done it, including me. You need very good seeing and high contrast detail facing the Earth. I never would have though such a thing is possible, but it is.

Try observing the very slight 'apparent' elongation of Io. Again you must have great seeing and it helps if Europa in the same high power field as a reference for being round. Io is often imaged as a dash against the Jovian cloud tops, however the visual impression is much more difficult. More folks should try it, actually this should be common knowledge. Folks may be surprised.

Edited by Asbytec, 29 July 2021 - 09:18 AM.


#17 bulletdodger

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Posted 17 August 2021 - 07:28 PM

Wow, got to get me some more aperature!
My 9.25 and 4 inch APO's I can resolve  moons as tiny discs, more like dots, but never imagined I could see anything like detail.
Need to up my game!


Edited by bulletdodger, 17 August 2021 - 07:29 PM.


#18 Asbytec

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Posted 22 August 2021 - 08:34 AM

Wow, got to get me some more aperature!
My 9.25 and 4 inch APO's I can resolve moons as tiny discs, more like dots, but never imagined I could see anything like detail.
Need to up my game!

Actually your 4" might do it, but your C9.25 is plenty. What you really need is very good seeing, and a little more magnification makes it a little easier on the eye to see resolved detail. And you have to catch Ganymede when its highest contrast features are facing the Earth.

The key thing to understand is the Jovian moons are not pure point source diffraction artifacts where no further resolution is possible. They are, in fact, very small extended objects (even in a 4" aperture) not much larger than the Airy disc of a 4" or 6" aperture. They are not really Airy discs at all, but a larger disc somewhere in the transition from Airy disc to extended object. So some very high contrast features can be seen at a very high spatial frequency. Resolution is possible.

On Ganymede, you may notice a bright spot on the disc. And if your lucky, you may see part of the disc is a shade darker. It'll look more like differences in albedo on the tiny disc than hard resolution like a lunar crater. But, you really need good seeing to "resolve" such small detail. Observing close to opposition and higher in the sky helps.

Actually detail on Ganymede, at least, should be common knowledge. It will be when more observers try and succeed. For Callisto you will need a larger aperture. It's detail is very low contrast. But Ganymede has some higher contrast features visible in modest apertures under favorable conditions. Io can be observed as a very slight ellipse (even though it's round, it's an albedo affect), and I'm unaware of anyone reporting detail on Europa.

Edited by Asbytec, 22 August 2021 - 08:47 AM.

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#19 scope dog

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Posted 22 August 2021 - 09:59 AM

Hi,

Here was a picture od Ganymede that I did with my MK91 Back in 2016, using a Lumeria 11mp camera, not sure whitch powermate.

My target was just messing around with the camera setting.

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#20 scope dog

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Posted 22 August 2021 - 10:08 AM

Here is the image that Ganymede came from.

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#21 Astrojensen

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Posted 22 August 2021 - 11:21 AM

I've seen Ganymede in a 30" dob. It looked like Mars at opposition in a 2". You could EASILY see some albedo features. 

 

I've never had good enough seeing to see any details on the Jovian moons in any of my own, much smaller scopes.

 

 

Clear skies!

Thomas, Denmark 


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#22 scope dog

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Posted 22 August 2021 - 12:54 PM

Like I said, I was just messing around. Actually I didn't notice the moon until 3 years later. I was board going through some pics But visual I don't think I could see it. It's a heck of a challenge, the rewards are slim.

#23 deepwoods1

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Posted 23 August 2021 - 12:11 AM

Holy moly. Just for fun I figured I’d look to answer this very same question! I thought I was “seeing” something about Ganymede Sunday morning, 12:30 am EST. Just for kicks I pulled out a 150 Mak as Jupiter was soooo bright. A storm was coming in, but at times the seeing improved vastly. Even though the GRS was turning away, I could make out details within. All the moons were disks. Just for fun, I studied each to see just what differences I could see. And Ganymede had albedo! A distinct light and dark area! This was visible in each eye. And at different times. I would not have thought it possible, but it was there, and I see by this thread that I’m not “ seeing” things. Wow! Clear and steady skies….


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#24 Asbytec

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Posted 23 August 2021 - 01:01 AM

Good on ya, Deep. Years ago I never thought it was possible either. An old friend challenged me to do the impossible. When I tried, the first thing I noticed as a glowing spot near the limb. At first I thought it was just a diffraction artifact. But on checking JPL Sim for Ganymede at the time, crater Osiris was located where the brighter spot was seen. In good seeing the diffraction artifact might be expected to be seen mostly in the center of the disc, rather it stayed near the limb. Confirmed on subsequent observations when I caught Ganymede at the same place in orbit. And some soft darkening was glimpsed, as well. That bright glowing spot was not always visible on Ganymede's disc, either, even in the same good seeing. Much later I happened upon Ganymede in a different location in its orbit and noticed another brighter spot. Again, checking with JPL Sim, sure enough another bright crater was on the Earth facing surface. But, again, the bright (what I thought was a diffraction artifact) was not always visible as Ganymede progresses in its orbit.
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#25 deepwoods1

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Posted 23 August 2021 - 01:11 AM

Ooohh, JPL simulator. That confirms what face I saw. Just being able to begin to discern something that small, that far away, is amazing. 


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