· Get a Cloudy Nights T-Shirt · Submit a Review / Article Click here if you are having trouble logging into the forums Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User You are not logged in. [Login] Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Astrophotography and Sketching >> Sketching Previous   Index   Next   Threaded   Pages: 1 ericj professor emeritus Reged: 02/17/05 Observations and Sketches of the Shrinking of GRS       #5725725 - 03/11/13 12:18 PM Edit   Reply   Quote Quick Reply   Hi, Since I posted this yesterday I changed my web page so all of the sketches can be seen simply by scrolling up and down. This makes it easier to compare how the GRS has changed over time: http://ejamison.net/recent_obs9.html#20 I was watching a TV program recently about Jupiter and it mentioned that Jupiter's Great Red Spot (GRS) is shrinking in length. I had heard this before but it got me wondering if I had seen and recorded this phenomena during my telescopic observations of the planet since 1973. In looking back at one of my earliest observations and sketches of Jupiter in 1973 with a 60mm refractor the GRS looked elongated to me: http://ejamison.net/telescope_advice.html#grs The same held true with Jupiter in 1974 when I was using a 4.25" reflector: http://ejamison.net/drawing.html#grs The GRS had faded to a dim gray color in 1976 but the Red Spot Hollow was noticeably elongated when I observed it with a 6" reflector in early 1977: http://ejamison.net/drawing.html#grs During my observations of Jupiter in the 1980's the GRS had a more oval shape to it: http://ejamison.net/jupiter101787.html My more recent sketches of Jupiter show the same thing: http://ejamison.net/jupiter052806.html So it seems likely I was recording the decreasing length of the GRS from 1973 until today. This is because leaving aside differences in the telescopes and magnifications employed over the years they all show the same trend in the data. To verify this I went I went to the Sky and Telescope website and came across a couple of articles that discussed how the GRS has been shrinking in length since the late 1800's. In the late 1800's it was almost 35 degrees wide. However by the time Voyager 1 and 2 visited Jupiter in 1979 it had shrank to 21 degrees. The height of the GRS has remained approximately the same. It confirmed also that between 1975 and 2010 the GRS has been shrinking in length from around 24 degrees to around 15 degrees. So my observations were accurate. It was a good thing I made sketches over the years as without them I may not have realized how much the GRS has changed over time if I had just taken notes. Clear Skies, Eric Jamison Edited by ericj (03/12/13 10:06 AM) Post Extras:       PeterDob professor emeritus Reged: 07/29/05 Loc: Carù, Italy Re: Observations and Sketches of the Shrinking of GRS [Re: ericj]       #5725975 - 03/11/13 02:24 PM Edit   Reply   Quote Quick Reply   Wow! Very interesting, Eric! It's yet another proof that also sketches can be of high scientific value, especially given the long period over which you made them and your obvious admirable experience. Congratulations for your work! Peter Post Extras:       Jef De Wit Carpal Tunnel Reged: 03/06/09 Loc: Hove, Belgium Re: Observations and Sketches of the Shrinking of GRS [Re: PeterDob]       #5726124 - 03/11/13 03:37 PM Edit   Reply   Quote Quick Reply   I can only echo PeterDob. Maybe you should put the drawings side by side. Post Extras:       JeanB Pooh-Bah Reged: 07/11/11 Loc: Montreal, Canada Re: Observations and Sketches of the Shrinking of GRS [Re: Jef De Wit]       #5726844 - 03/11/13 08:54 PM Edit   Reply   Quote Quick Reply   Amazing set of sketches through time Eric! This shrinking story is terrific. I agree with Jef, your should try a composite side by side. Jean Post Extras:       ericj professor emeritus Reged: 02/17/05 Re: Observations and Sketches of the Shrinking of GRS [Re: PeterDob]       #5727728 - 03/12/13 09:42 AM Edit   Reply   Quote Quick Reply   Hi Peter, Thanks for the very kind words. After watching the TV show I started going back through my old astronomy log books and was surprised how much the GRS has shrunk over time. I had no idea when I first started sketching at the eyepiece in 1973 that someday the sketches could show pronounced changes to the GRS. Best, Eric Jamison Post Extras:       ericj professor emeritus Reged: 02/17/05 Re: Observations and Sketches of the Shrinking of GRS [Re: Jef De Wit]       #5727755 - 03/12/13 09:54 AM Edit   Reply   Quote Quick Reply   Hi Jef, Thanks for the very kind words. Thanks for your suggestion about putting the drawings side by side. I changed my web page so all of the sketches can be seen simply by scrolling up and down. This makes it easier to compare how the GRS has changed over time: http://ejamison.net/recent_obs9.html#20 Best, Eric Jamison Post Extras:       ericj professor emeritus Reged: 02/17/05 Re: Observations and Sketches of the Shrinking of GRS [Re: JeanB]       #5727766 - 03/12/13 09:59 AM Edit   Reply   Quote Quick Reply   Hi Jean, Thanks for the very kind words. I changed my web page so all of the sketches can be seen simply by scrolling up and down. This makes it easier to compare how the GRS has changed over time. Best, Eric Post Extras:       frank5817 Postmaster Reged: 06/13/06 Loc: Illinois Re: Observations and Sketches of the Shrinking of GRS [Re: ericj]       #5731245 - 03/13/13 10:10 PM Edit   Reply   Quote Quick Reply   Eric, That is an interesting change in the shape and size of the GRS. I have some sketches that go way back, I should pull them out and have a look. Thanks for posting and very interesting. Frank Post Extras:       ericj professor emeritus Reged: 02/17/05 Re: Observations and Sketches of the Shrinking of GRS [Re: frank5817]       #5745671 - 03/20/13 05:09 PM Edit   Reply   Quote Quick Reply   Frank, Thanks. I would be interested in seeing your sketches. Best, Eric Post Extras:       frank5817 Postmaster Reged: 06/13/06 Loc: Illinois Re: Observations and Sketches of the Shrinking of GRS [Re: ericj]       #5746788 - 03/21/13 01:31 AM Attachment (8 downloads) Edit   Reply   Quote Quick Reply   Hi Eric, Here is one from 1980 and I did draw the GRS elongated. I would not consider this good evidence since I did not sketch Jupiter with reliability before about 7 years ago. Frank Post Extras:       ericj professor emeritus Reged: 02/17/05 Re: Observations and Sketches of the Shrinking of GRS [Re: frank5817]       #5796594 - 04/13/13 01:06 PM Edit   Reply   Quote Quick Reply   Hi Frank, Nice sketch thanks for posting it. Best, Eric Post Extras:       ericj professor emeritus Reged: 02/17/05 Re: Observations and Sketches of the Shrinking of GRS [Re: ericj]       #5796610 - 04/13/13 01:15 PM Edit   Reply   Quote Quick Reply   Hi, I recently came across a sketch of Jupiter and the GRS made by Étienne Léopold Trouvelot of Jupiter on November 1, 1880 using the U.S. Naval Observatory 26" refractor: http://digitalgallery.nypl.org/nypldigital/dgkeysearchresult.cfm?parent_id=44... I noticed that even accounting the larger aperture he was using compared to mine the length GRS back then was significantly longer than what I recorded: http://ejamison.net/recent_obs9.html#20 Clear Skies, Eric Jamison --------------------- http://ejamison.net/ Post Extras:       frank5817 Postmaster Reged: 06/13/06 Loc: Illinois Re: Observations and Sketches of the Shrinking of GRS [Re: ericj]       #5797634 - 04/13/13 10:55 PM Edit   Reply   Quote Quick Reply   Hi Eric, The drawings by Trouvelot are fine ones. He was a gifted astronomical artist of the late 19th century. I am sure his drawing are faithfully accurate. Frank Post Extras:       ericj professor emeritus Reged: 02/17/05 Re: Observations and Sketches of the Shrinking of GRS [Re: frank5817]       #5798885 - 04/14/13 05:03 PM Edit   Reply   Quote Quick Reply   Hi Frank, Thanks, I added a link that shows some of his other astronomical sketches that include lunar ones as well. Best, Eric Jamison Post Extras:       frank5817 Postmaster Reged: 06/13/06 Loc: Illinois Re: Observations and Sketches of the Shrinking of GRS [Re: ericj]       #5801801 - 04/15/13 11:55 PM Edit   Reply   Quote Quick Reply   Thanks Eric, I am familiar with some of these but not all of them. The one of Mare Humorum is especially good. Here is a solar sketch he did that I posted on ASOD a while back (April 29,2007). http://www.asod.info/?p=125 His planet sketches and that one of Jupiter with the great red spot are very special. Frank Post Extras:       ericj professor emeritus Reged: 02/17/05 Re: Observations and Sketches of the Shrinking of GRS [Re: frank5817]       #5828578 - 04/28/13 03:05 PM Edit   Reply   Quote Quick Reply   Hi Frank, Thanks for the link, the sketch shows a lot of fine detail. With regards to his comet sketch I had read that sometimes observers back then would make a sketch of a comet through a telescope and then add the observatory in the foreground. So the resulting sketch is not what they see with the unaided eye. Best, Eric Post Extras:       kenrenard scholastic sledgehammer Reged: 12/13/12 Loc: Dunmore, PA Re: Observations and Sketches of the Shrinking of GRS [Re: ericj]       #5830365 - 04/29/13 02:27 PM Edit   Reply   Quote Quick Reply   Eric, Just came across your site. Lots of great information there. This is some of the info I have been looking for. I just started sketching Jupiter in the past month and I am trying to learn more about the planet. Nice Work. I will be spending more time reading on your site. Ken Post Extras:       ericj professor emeritus Reged: 02/17/05 Re: Observations and Sketches of the Shrinking of GRS [Re: kenrenard]       #5834292 - 05/01/13 12:39 PM Edit   Reply   Quote Quick Reply   Hi Ken, Thanks for the kind words about my website, I try to add new material as time permits. There are some of my Jupiter sketches on the Introduction to Planetary Sketching page: http://ejamison.net/drawing.html Also on the Jupiter Nomenclature page: http://ejamison.net/jupiter_nomenclature.html And on the Jupiter Sketches and Observations page: http://ejamison.net/jupiter.html I observed Jupiter last night but the seeing wasn't very good. If I can answer any questions for you let me know. Best, Eric Jamison Post Extras:       kenrenard scholastic sledgehammer Reged: 12/13/12 Loc: Dunmore, PA Re: Observations and Sketches of the Shrinking of GRS [Re: ericj]       #5834349 - 05/01/13 01:00 PM Edit   Reply   Quote Quick Reply   Thanks Eric, I am enjoying reading your posts. I also tried at Jupiter last night and had little luck. Very Windy here. Ken Post Extras:       Pages: 1 Previous   Index   Next   Threaded   Extra information 1 registered and 4 anonymous users are browsing this forum. 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