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Change in the Appearance of Jupiter, South dark belt missing
4th rock from th...
post May 17 2010, 01:26 PM
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QUOTE (Decepticon @ May 16 2010, 10:44 PM) *
...The great red spot looks different.


Let me add a Pioneer 11 image that I processed some time ago:




The GRS changes are apparent, but besides that the band structure around it is also quite different. Fascinating!


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tedstryk
post May 17 2010, 01:45 PM
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Well, for crying out loud, look at how much difference it was in 1879. This photo was taken in blue light, which makes bands and especially the red spot appear darker, but look at how big the red spot is and look at how bright the area is around it. Jupiter had its familiar, two big band structure before and after this.
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elakdawalla
post May 17 2010, 04:23 PM
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QUOTE (4th rock from the sun @ May 17 2010, 05:26 AM) *
Let me add a Pioneer 11 image that I processed some time ago:
That's really nice work -- can you explain a little more about how you did the processing?


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4th rock from th...
post May 17 2010, 05:25 PM
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Well, besides the normal processing techniques such as level adjustments, for the Pioneer images I redid the color composites by processed color and luminance separately.

So the processing steps would be something like this:

- Find and stack the best copies of the image to reduce noise, scan and print artifacts. Two good copies are enough to recover the original 6bit dynamic of the images.

- From the stacked master frame, I made two copies. One I change to B&W and process to bring out faint details. The other I use to create a color image as well balanced as possible. For that I mix the red and blue channels to recreate green (although this was already done on most of the original images). I may have to apply some with pass filters to get rid of color gradients.

- I recombine the luminance from the first version of the image with the color information from the second version, adjusting saturation, gamma and overall look using Cassini images as a visual reference.

- Finally, I warp the image to correct from the spin scan image distortion, using a simulated Jupiter disk with a similar view point that came from Celestia.

I think that final results are close to what the original data shows and only geometry is still somewhat off.


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PDP8E
post May 17 2010, 05:35 PM
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I found this image of Jupiter in a textbook, 'A Treatise on Astronomy" by Elias Loomis, 1893

...the passage after the 'plate' reports to us that the 'ancients' (astronomers more than 50 years ago) observed that the bands have broken up before...

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4th rock from th...
post May 17 2010, 10:37 PM
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Look here for planetary images acquired between 1890 and 1977:

Database of planetary images (BDIP) : http://www.lesia.obspm.fr/BDIP/


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post May 18 2010, 08:21 AM
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The Red Spot should be easier to see in small telescopes now.
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4th rock from th...
post May 18 2010, 05:17 PM
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Looking into the historical images, Jupiter looks similar to today around 1904:

Attached Image


By 1906 it had returned to it's normal appearance:

Attached Image



Very dynamic planet indeed.
I didn't go through all the images, so probably there's lots of photographic evidence for the other fading cycles, and this really shows the importance of having old images accessible, even if their quality is sometimes low.


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tedstryk
post May 18 2010, 06:43 PM
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What a great site! I have long wished someone would compile something like that.


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4th rock from th...
post May 18 2010, 09:02 PM
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I already tried to make some RGB composites out of those old Jupiter images, but each original image is several minutes apart and the planet's rotation has shifted features too much. Some of the images are quite good for the time and techniques (chemical photography) used.


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tedstryk
post May 19 2010, 03:06 PM
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I had done some of that (and I think I posted one example) right before my computer crash in 2005. The project and scans were lost, and I never took it back up. Granted I was working with images of Mars, and images of Mars benefit from the planet's slower rotation.

Edit - Found it - Mars in 1909.


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PDP8E
post May 20 2010, 01:24 AM
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Ted,
Nice work with the 1909 Mars image! (how you got RGB is still a mystery to me...but)
These two features popped out as if the image was taken yesterday in a good sized 'scope

Attached Image


(... I think I'm right ?...)

Thanks



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tedstryk
post May 20 2010, 01:52 AM
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Yes, you are right. And I did the color the old fashioned way - I stacked a red, a green, and a blue image.


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4th rock from th...
post May 20 2010, 09:08 AM
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Yes, nice classic Mars image. If you compare it to the current planet, there are changes and the albedo patterns. Syrtis Majoris does look somewhat different, with an extension to the left that is not visible now.

I think that Jupiter or Saturn would benefit more from that reprocessing effort, because the atmospheric features are less contrasted and have different colors. One long standing question (for me) is if the general color of Jupiter has changed or not over the decades, independently of the cameras and filters used.
The GRS looks less saturated today than in the past, although the bands still look very much the same... But it might as well be the other way around (the bands might be getting more contrasted).

It's easy to dismiss any differences based on poor hardware and filter combinations (like Voyager's OGV vidicon compared to Cassini RGB CCD images... ). Perhaps satellite transits can be used to color balance the old images.


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galileo
post May 20 2010, 11:49 AM
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QUOTE (Sunspot @ May 18 2010, 02:21 AM) *
The Red Spot should be easier to see in small telescopes now.

What would be the smallest size of telescope your talking about?
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