Change in the Appearance of Jupiter, South dark belt missing |
Change in the Appearance of Jupiter, South dark belt missing |
May 17 2010, 01:26 PM
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#16
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Member Group: Members Posts: 378 Joined: 21-April 05 From: Portugal Member No.: 347 |
...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! -------------------- _______________________
www.astrosurf.com/nunes |
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May 17 2010, 01:45 PM
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#17
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
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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May 17 2010, 04:23 PM
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#18
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Administrator Group: Admin Posts: 5172 Joined: 4-August 05 From: Pasadena, CA, USA, Earth Member No.: 454 |
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?-------------------- My website - My Patreon - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
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May 17 2010, 05:25 PM
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#19
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Member Group: Members Posts: 378 Joined: 21-April 05 From: Portugal Member No.: 347 |
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. -------------------- _______________________
www.astrosurf.com/nunes |
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May 17 2010, 05:35 PM
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#20
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Member Group: Members Posts: 808 Joined: 10-October 06 From: Maynard Mass USA Member No.: 1241 |
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... -------------------- CLA CLL
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May 17 2010, 10:37 PM
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#21
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Member Group: Members Posts: 378 Joined: 21-April 05 From: Portugal Member No.: 347 |
Look here for planetary images acquired between 1890 and 1977:
Database of planetary images (BDIP) : http://www.lesia.obspm.fr/BDIP/ -------------------- _______________________
www.astrosurf.com/nunes |
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Guest_Sunspot_* |
May 18 2010, 08:21 AM
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#22
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Guests |
The Red Spot should be easier to see in small telescopes now.
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May 18 2010, 05:17 PM
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#23
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Member Group: Members Posts: 378 Joined: 21-April 05 From: Portugal Member No.: 347 |
Looking into the historical images, Jupiter looks similar to today around 1904:
By 1906 it had returned to it's normal appearance: 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. -------------------- _______________________
www.astrosurf.com/nunes |
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May 18 2010, 06:43 PM
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#24
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
What a great site! I have long wished someone would compile something like that.
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May 18 2010, 09:02 PM
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#25
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Member Group: Members Posts: 378 Joined: 21-April 05 From: Portugal Member No.: 347 |
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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www.astrosurf.com/nunes |
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May 19 2010, 03:06 PM
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#26
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
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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May 20 2010, 01:24 AM
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#27
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Member Group: Members Posts: 808 Joined: 10-October 06 From: Maynard Mass USA Member No.: 1241 |
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 (... I think I'm right ?...) Thanks -------------------- CLA CLL
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May 20 2010, 01:52 AM
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#28
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
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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May 20 2010, 09:08 AM
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#29
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Member Group: Members Posts: 378 Joined: 21-April 05 From: Portugal Member No.: 347 |
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. -------------------- _______________________
www.astrosurf.com/nunes |
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May 20 2010, 11:49 AM
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#30
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Newbie Group: Members Posts: 11 Joined: 31-May 09 From: Iowa Member No.: 4806 |
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