32 replies to this topic

[KBHornblower]

              I haven't given the King of Planets any love this year, I'm afraid. But when I was last very active in the Hobby back in 2013-14, the GRS was certainly visible. But it was not red. More like pastel pink. 

              I know it changes colors & even size, so I do not know if its visible at all this year. Anyone who has seen it?

 

            Clear Skies,

               Matt.

Yes, I have seen it several times in recent weeks.  It is considerably smaller than it was some decades ago, but plenty bold in good seeing.

[E_Look]

I think this nails it fairly well.  But still, some will not necessarily see Jupiter behave this way.  Why?  IME it is because different observers focus on different aspects of the planet.  So when one's primary focus is on the major high contrast features then all of a sudden the planet can take lots of magnification.  But for those whose focus is more on the subtle stuff, then the planet cannot take as much magnification, as it should not be able to given the physics of the situation.  So it really depends on where one's focus is because where their focus is, is where their perception system then either accentuates or filters out the information their eye is receiving.  You see this phenomena in action a lot when people post equipment comparison reports that often say they did not see some feature with one eyepiece but did with the other, then when they went back to check the other eyepiece it was there after all.  So don't be fooled into thinking that one's perception of reality through the use of their senses is actually reality.  It is not.  Instead it is the reality as seen through the "lens" of their perception which has been altered/changed/modified by their unique genetic predispositions, past experiences, prior knowledge, emotions, preconceived notions, self-interest, and cognitive distortions.  As such it is not an accurate representation of what the reality truly is.  All part of being human!
 

Ah, Bill!  You have just put the entire eyepiece forum moot, and not just those on CN.

What you said should be obvious, especially when one considers that vision is comprised of a train of events and things, from what the air is doing, through lenses, including our natural ones, past the physiological variation, and not just person-to person, but from moment-to-moment on our retinas, any quantum, electrical phenomena we can't know about from between there all the way to the visual cortex... and then one's personality comes into play...

 

... eh, I guess, just enjoy it, unless it's howling wind and cold or burning hot, then go inside... where I get on CN and find out what others saw on the same object that night!

[areyoukiddingme]

I think Bill's and CPKs points about attention might be the thing that explains why we are disagreeing.

 

The low contrast stuff like blue barges, and small subtle storm festoons within the bands, and details around the GRS, and often the fine bands at the poles are quite low contrast.

 

In comparison, seeing the major bands, the GRS, shadow transits, are all large and relatively high contrast features.

 

So if you are trying for the former category of detail, my experience is that I'm usually doing better at relatively lower magnifications--250x at most.

 

But for seeing those other higher contrast features, then that probably does not differ from the kinds of magnifications I'd use for Mars and Saturn.

 

Of course, this still leaves on the table the question as to why low contrast details are not being seen better (at least for some of us). Could it be light scatter effects from the optics get more detrimental at higher magnifications?

 

Could it be the eye is doing the scattering instead (or as well as?).

 

Could it be that we "the low mag crowd" are getting it wrong because of some illusion?

[Redbetter]

My experience with Jupiter has been that seeing that fully supports 250x in an 8, 10 or 20" is revealing a high intermediate level of detail, not what I consider the truly small stuff.  The 250x to 275x level of resolution for planetary features is a notch past where my 110ED or 127 Mak top out for example, even when the seeing is much better than that.   Things are just starting to get interesting at this point, rather than providing a high water mark for large aperture.  

 

In some of these discussions, I wonder if folks have actually observed many of the smaller details.  There is another range that emerges when the seeing settles enough to support 350x and beyond.   The 8" SCT is running out of gas at about 300+ actual (Jupiter and Mars), but the 10" and 20" are revealing ever smaller features. These smaller features are not well recognized or observed at 250x:   The inner structure of the GRS is increasingly resolved, the smallest of the white ovals in the SSTB, red ovals in other belts/near the poles, etc.  Very good planetary seeing will show the moons transiting all the way across even when the contrast is somewhat muted vs. the features below.  This sort of seeing is not common here, and even on the few nights it does occur, it rarely lasts more than an hour before it degrades a notch or two (diurnal breezes.)  

 

Even on the nights here where I am able to use 350 or even a little over 400x briefly with the 10", things are not quite as stable as I have experienced on the best nights further south.   There is another level beyond this, when the seeing is truly excellent, where 500x and above are steady;  but that is not for the 10", it is where the 20" will really show what it can do.

 

Keep in mind that I don't magnify for magnification's sake or based on simple rules of thumb.  I stop when I find the optimum for the seeing/scope/my eye:  the optimum is the last level that is stable enough to reveal things that might only be suspected at the next increment below, or increasingly blurred/shifting in focus at the next level above.

 

I am puzzled by calling clouds around Olympus Mons "high contrast."  They aren't, or at least not typically.  The clouds typically aren't as high albedo as the polar cap, and they are set against some of the brighter terrain.  Often they are missing, sometimes allowing Olympus to be detected as patch in its own right, and not responding to filters that would reveal the clouds.    They seem quite variable (with the Arsia Mons area being even more so) with level and contrast changing in appearance over hours or days and probably seasonal as well.  The visibility is also dependent on the seeing...very much like the white ovals in the SSTB/SSTB which often have only muted contrast with the varying intensity of the beige/tan belts. (As such those ovals serve as indicators of the seeing.)  

[E_Look]

I have able few years ago to see some of the lower-level detail you mention on Jupiter, such as larger festoons, or larger barges, larger ovals, maybe a storm, but some of these latter are on the whiter side, making them hard to see well.  But it does require better seeing; I mean, a little waviness is acceptable, but like we've had around NYC, it's not.  Over about three years, (really, several, sporadic nights), I saw the GRS go from red-gray to pinkish to salmon to gray (and this year, haven't seen it yet; less time these days).  And, I noticed it shrunk as well, but for a short time, there as notch or hook around the pocket it sat in on the SEB.

 

I observed this with a 8" Newtonian, and optimal magnification in general about 200x-250x, depending on conditions.

[luxo II]

My experience with Jupiter has been that seeing that fully supports 250x in an 8, 10 or 20" is revealing a high intermediate level of detail, not what I consider the truly small stuff. The 250x to 275x level of resolution for planetary features is a notch past where my 110ED or 127 Mak top out for example, even when the seeing is much better than that. Things are just starting to get interesting at this point, rather than providing a high water mark for large aperture.

In some of these discussions, I wonder if folks have actually observed many of the smaller details. There is another range that emerges when the seeing settles enough to support 350x and beyond. The 8" SCT is running out of gas at about 300+ actual (Jupiter and Mars), but the 10" and 20" are revealing ever smaller features.

Pretty well summed up... on a good night 250-300 is where the SCTs are running out yet Alex’s MK91 and my 10” are just cruising, in the right conditions they go to 450-600X. We seem to have about 1-2 night a year like that in Sydney.

[HellsKitchen]

I've had success with my 8" dob at 400x during one very good night in July this year. During those steady moments I had chills up my spine. Generally though, I find Jupiter less tolerant of magnification than Mars or Saturn. I suspect that the myriad of fine low contrast features wash out easier than the more robust, hard edged higher contrast detail on Mars and Saturn. 

Edited by HellsKitchen, 07 December 2020 - 01:54 AM.

[barbie]

My skies typically support 150X-200X on Jupiter with my small scopes when Jupiter is at its highest point in the sky. This past summer, I could get to just over 200x when Jupiter was on the meridian.