Just thought I would share this 5 minute video by Carl Sagan (RIP 1996) quickly and exquisitely (in '70s style) explaining Eratosthenes proof of a round earth and determining its circumference. Quite amazing that there are "flat earthers" out there today! I think this is a wonderful video.. he was a great teacher. -- Born around 276 B.C. in Cyrene, Libya, Eratosthenes was able to accomplish this in part because of his education in Athens. There, he became known for his achievements in many different fields, including poetry, astronomy, and scientific writing. His activities became so talked about, in fact, that Ptolemy III of Egypt decided to invite him to Alexandria to tutor his son. Later, he would become the head librarian of the Library of Alexandria. The Library of Alexandria was a hub of learning at the time, attracting scholars from across the known world. Eratosthenes was able to rub shoulders with the likes of Archimedes while continuing his own learning. ----- I do not own a Ptolemy III... but here is a Ptolemy II - he at least walked this round earth at the same time as Eratosthenes. Ptolemy II Philadelphos AE 27mm Obol. Alexandria mint. Laureate head of Zeus-Ammon right / Eagle standing left on winged thunderbolt; monogram and shield to left, tiny o between legs -- I hope you liked the video... I miss Carl Sagan. For those of you who are younger and do not know him you can find more of Sagan's insightful videos on youtube..etc. He was great. (sorry title states 2 minutes but found a better video @5 minutes and can't change the title)
I always say that Eratosthenes would be rolling over in his 2200-year-old grave if he knew that the flat earthers (mostly in the USA, it must be said) are becoming more popular today. Utterly ridiculous nonsense in our times, really.
I always enjoyed watching Carl Sagan. He was able to explain things in a manner that was easily understood. (At least to me).
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I was fortunate enough to have a class with Carl Sagan in 1969 at Cornell. There were only 12 of us. We would meet and then retire to his house where we had cider and cookies with him and his wife. I estimate he would have been about 32 at the time. Now, about those flat earthers… I always assume they are just having a laugh. It seems to be a sendup of all the seriousness in religion and science. In religion, you have sacred texts that cannot be questioned, even though they are full of internal contradictions and make nearly no sense - especially as they date from vastly different cultures from today (although human nature seems the same). Nonetheless you had serious folks spending millennia trying to make it all make sense and hammer it into a dogma. In science you have equally serious people trying to make sense of a chaotic natural world. What better sendup than to have a mock-serious assertion of something that is so obviously wrong, and to have all the seemingly serious discussions of why it must be so and what it all means. I mean, even sailors long before Columbus’s voyage could see the masts of distant ships rise up over the horizon. Everybody simply could see it was round. Put me and a flat-earther in a bar and I bet we’ll have a great time riffing off each other about the wonderful ridiculousness of it all.
Portrait of Ptolemy III Mnaieion of Ptolemy IV 219-217 BC Obv, Bust of Ptolemy III right radiate wearing aegis and with trident over left shoulder. Rv, Radiate filleted diadem resting on cornucopia Lorber CPE 888 Dies 3/10 27.82 grms 27 mm Photo by W. Hansen What is remarkable about this coin is that the adjunct objects of three gods Zeus (aegis) Poseidon (trident) and Helios (rays) have all been appropriated for this image. In this image we can see why Ptolemy IV would want to honor his father. The aegis has always been appropriated by the Ptolemies but the trident suggests his concern for his navy and the radiate crown recalls his success against the Seleukids which included his march into Mesopotamia. While it is true that all three objects do convey something of the career of Ptolemy III it is also noteworthy that these same three adjuncts all but overwhelm the image of the man giving this image a strong oriental vibe in which the trappings of office are of greater importance than the image of the individual.
There is a Carl Sagan quotation (meme) here that has been floating around the Internet recently about how Carl Sagan predicted the cultural and educational morass we would eventually be in by now because of the misuses of technology and devolution of society....
Sagan has been one of my idols since I was 11 or 12. I owe my critical thinking skills to him. I would've loved to have had cider and cookies with the man!
Not to be Mr. Obvious, and I'm sure you already know this - but since I didn't see it in your description - that Ptolemy II obol has a really, really nice trident countermark. I like it! I wish I had one to share, but I do not . There's some examples on this great site: http://ptolemybronze.com/ptolemy_series.html That Eratosthenes was a smart guy. If I were around back then, I'd've probably argued with him about a flat earth. Science and math were never my strong suits.
Not only a great teacher but also a outstanding visionary and predictor of future events. Never to be forgotten, RIP Carl Sagan. Dr. Tyson is great also, Thanks for the posts Clavdivs and Andres2.
This is one of the best threads I have had the pleasure of reading. I started early on studying science and science fiction. My father was an avid reader and I caught the bug from him. One of my favorite set of books is the Foundation Series that Isaac Asimov wrote to entertain and educate us. I was twelve and in the 7th grade. Since then, I have migrated to Louis L'Amour's westerns, which they, too, have entertained and educated me, albeit, different genres. I also love to collect and study coins. This website is one of the best, or best, place to learn about many things from collectors from all walks of life with differing backgrounds, education, and life. Thank all of your your teaching me more than many other sources about many things. As my son has told me, "You are my hero." The same goes to this class of people. You, too are my heroes by teaching and endearing me to my coin collecting.
