Aah Cassini at Japet. Another pretty Proust madeleine. Your article is also such a beautiful reminder of what the human mind is able to infer, centuries before having the means to confirm it in situ. Well done, Giovanni Domenico! A comment perhaps: your “ahem” before “Galilean” suggests that Galileo may have lacked modesty. No doubt, but maybe not in this case? He proposed to name them after his protectors, the Medici, isn’t it? And a question: you mention in the middle of your article a white line detected along Japet’s equator by the Voyagers, and already identified at the time as a high mountain range. I haven’t found any reference to that discovery in 180 or 1981, and you mention later that the equatorial mountain range was discovered 6 days before Christmas. In the end, is this a Voyagers’ or Cassini’s discovery? Thanks!
Bruno ... your name is familiar. Where have we crossed paths before? Twitter? Anyway, my ahem was not what you think. It was just recognizing, with humor, that OF COURSE it's obvious ... the satellites that Galileo discovered would be named after him. And I did not state that the white mountain peaks were discovered by Cassini. I stated, "In those October images (below), we were approaching from the south, looking at the transition between the dark and bright sides, and immediately saw a portion of a big basin in the southern hemisphere, and recognized a line of white features that had been discovered in Voyager images." What we on Cassini discovered was the raised equatorial ridge that went ~110 deg around Iapetus. In other words, it was not known at the time of Voyager that the newly discovered peaks were part of a major, extensive, geomorphological feature. I hope that helps!
Thanks so much for another great read. The event was unforgettable. The descent footage was jaw-dropping and the surface film nothing short of a triumph. I loved the moving shadow image across the field of vision as the untethered descent 'chute ' sailed overhead out of shot - just priceless. But for all it's otherworldliness, the surface seemed astonishingly familiar. It seems wherever we look in the Solar System, it's the same processes at work- just different materials at play. Thanks again, and Happy belated anniversary!
Maybe it's because Galileo was the first to turn a telescope upwards! It was the very consequential moment that humanity began spying on the universe. And he discovered all 4 moons at the same time. So, he really deserves that recognition. And Cassini's name is given to the division in Saturn's rings that he discovered. So, he knows we love him, too.
We have such wonderful technology today- and getting better! This is a wonderful science, for both amateurs and professionals. Happy New Year, Carolyn!
Hi Carolyn. I have wondered this for years. Do Scientists assemble a Periodic Table of the Elements for each moon or planet we visit ? Would the Table on Mars and Earth be almost identical ? Thanks, Ernie.
Puzzling question. The PT is the categorization of elements (ie atoms w/ different # of protons in the nucleus) based on the structure of their electron clouds. That is universal. It will be the same everywhere. (Well, maybe things get munged close to a black hole.) It has nothing to do with planets or you or me.
Of course you've probably already thought about this, but could the material be from the theoretical source of Saturn's rings? I remember watching a documentary where I believe you were talking about a possible icy moon exploding as it reached Saturn's roche limit, causing its rings. Are the same elements found on Iapetus, Phoebe, etc also found in the rings? PS. I wrote a poem/song about Saturrn's Roche limit, inspired by your work. Hope you like it: https://youtu.be/GHol4WHlveM
I doubt it. Iapetus is vastly more distant from Saturn than the rings. And the distribution of material wouldn't look like it does on Iapetus. It would be more uniformly distributed.
Fantastic. I am a little confused in some of the images about the direction of solar illumination. How far around the circumference does the ridge extend? I also love the landslide image.
Aah Cassini at Japet. Another pretty Proust madeleine. Your article is also such a beautiful reminder of what the human mind is able to infer, centuries before having the means to confirm it in situ. Well done, Giovanni Domenico! A comment perhaps: your “ahem” before “Galilean” suggests that Galileo may have lacked modesty. No doubt, but maybe not in this case? He proposed to name them after his protectors, the Medici, isn’t it? And a question: you mention in the middle of your article a white line detected along Japet’s equator by the Voyagers, and already identified at the time as a high mountain range. I haven’t found any reference to that discovery in 180 or 1981, and you mention later that the equatorial mountain range was discovered 6 days before Christmas. In the end, is this a Voyagers’ or Cassini’s discovery? Thanks!
Bruno ... your name is familiar. Where have we crossed paths before? Twitter? Anyway, my ahem was not what you think. It was just recognizing, with humor, that OF COURSE it's obvious ... the satellites that Galileo discovered would be named after him. And I did not state that the white mountain peaks were discovered by Cassini. I stated, "In those October images (below), we were approaching from the south, looking at the transition between the dark and bright sides, and immediately saw a portion of a big basin in the southern hemisphere, and recognized a line of white features that had been discovered in Voyager images." What we on Cassini discovered was the raised equatorial ridge that went ~110 deg around Iapetus. In other words, it was not known at the time of Voyager that the newly discovered peaks were part of a major, extensive, geomorphological feature. I hope that helps!
Thanks so much for another great read. The event was unforgettable. The descent footage was jaw-dropping and the surface film nothing short of a triumph. I loved the moving shadow image across the field of vision as the untethered descent 'chute ' sailed overhead out of shot - just priceless. But for all it's otherworldliness, the surface seemed astonishingly familiar. It seems wherever we look in the Solar System, it's the same processes at work- just different materials at play. Thanks again, and Happy belated anniversary!
Came late to it, but great article about this weird, two-faced walnut moon!
Thank you! There will be more. Stay tuned.
Great read. More of these please! All the very best for 2025.
Ok!
Cool read. If the moons Galileo discovered are considered the “Galilean Moons”, why ain’t the big moons of Saturn considered “ Cassinian Moons”? 😂
Maybe it's because Galileo was the first to turn a telescope upwards! It was the very consequential moment that humanity began spying on the universe. And he discovered all 4 moons at the same time. So, he really deserves that recognition. And Cassini's name is given to the division in Saturn's rings that he discovered. So, he knows we love him, too.
We have such wonderful technology today- and getting better! This is a wonderful science, for both amateurs and professionals. Happy New Year, Carolyn!
Thank you!
Great review Carolyn! We keep learning more about our tiny part of the universe. Thank you.
Thank you!
Excellent! Thanks!
Thank you!!
What great science!!! Happy New Year Carolyn!!!
Thanks, Greg! Great science indeed.
Hi Carolyn. I have wondered this for years. Do Scientists assemble a Periodic Table of the Elements for each moon or planet we visit ? Would the Table on Mars and Earth be almost identical ? Thanks, Ernie.
Puzzling question. The PT is the categorization of elements (ie atoms w/ different # of protons in the nucleus) based on the structure of their electron clouds. That is universal. It will be the same everywhere. (Well, maybe things get munged close to a black hole.) It has nothing to do with planets or you or me.
Of course you've probably already thought about this, but could the material be from the theoretical source of Saturn's rings? I remember watching a documentary where I believe you were talking about a possible icy moon exploding as it reached Saturn's roche limit, causing its rings. Are the same elements found on Iapetus, Phoebe, etc also found in the rings? PS. I wrote a poem/song about Saturrn's Roche limit, inspired by your work. Hope you like it: https://youtu.be/GHol4WHlveM
I doubt it. Iapetus is vastly more distant from Saturn than the rings. And the distribution of material wouldn't look like it does on Iapetus. It would be more uniformly distributed.
Thank you Carolyn for this inspiring example of rigor curiosity and accomplishment. Hoping to see you soon.
Debbie
Thanks Debbie! The 'rigor' in all that nearly killed me, but I survived to tell the tale!
Fantastic. I am a little confused in some of the images about the direction of solar illumination. How far around the circumference does the ridge extend? I also love the landslide image.
Happy new year.
Hi Tom! Happy New Year! The ridge extends ~110 deg in full. Which image is confusing to you?
Happy New Year, Dr. Porco!
Something hilarious for you. I saw it and instantly thought of you. :)
https://www.reddit.com/r/mildlyinteresting/comments/edp992/this_golden_recordrocket_pizza_cutter/
Take care!
Oooh! Oooh! I want one. Thanks!!
Happy new year, Carolyn. And thanks for this series of articles. It's great to remember Cassini and your work.
Happy New Year ! Loved the article