Tag Archives: Persia

Longitude doesn’t represent distance—there, I said it

In the last post I said I’d tell you how Eratosthanes knew how many degrees of longitude Benghazi is from Alexandria.

We know that lines or parallels of latitude are about 69 miles apart. Latitude measures degrees of two 90° quarter-circles, each starting at the Equator and ending at the poles. The Equator is 0° and the North & South poles are 90°.

Longitude measures time. Or to be more precise, longitude converts time into degrees of a 360° circle. “WHAT?” I hear you holler as you spring from your comfy chair. “Have you finally lost your marbles, Manders?”

Al-Biruni (973–1048), another one of those amazingly-accomplished scholars

Ptolemy’s geocentric vision of the universe reckoned that Earth doesn’t move—she is stationary while the heavens whirl around her. But a Persian scholar, Al-Biruni, thought that the Earth spins on her axis—just like the globe in your classroom. If that were true (and of course it is), you’ll realize that the Earth spins all the way around every day, every 24 hours.

I drew 24 sections on this sphere—for the 24 hours it takes for Earth to spin around on her axis. Each line is a meridian, a longitude line.

THAT CHANGES EVERYTHING! Mapmakers could divide the Earth’s surface into 24 units. Each unit would represent one hour. Each unit would also represent 15 degrees. Why? Because there are 360 degrees in a circle. 360 divided by 24 equals 15. Now I ask you, who was it who divided the day into two 12-hour halves? Who was it who came up with Base Sixty counting, which makes it so easy to divide 360 by 24? Who? WHO?

Thanks, Sumerians!

The Sumerians, that’s who! I love those guys!

Getting back to Eratosthanes’ experiment: if that lunar eclipse began at 12:36 am Alexandria time and midnight Benghazi time, Eratosthanes knew that Benghazi is 36 minutes west of Alexandria. The Earth rotates on her axis 360° every day, 15° every hour, and 1° every 4 minutes. So, 36 minutes difference in time from Alexandria to Benghazi ÷ 4 = 9 degrees of longitude. Thinking of a chunk of time as a chunk of a circle, Eratosthanes could confidently mark Benghazi’s longitude on a map.

https://www.britannica.com/biography/al-Biruni

Back to the beginning of The Western Civ User’s Guide to Time & Space

Meanwhile, in Persia—

With only a jug of wine, a loaf of bread and thousands of calculations, Omar Khayyám works out a new calendar

ad1075. In Persia, using the Hindu-Arabic decimal system, Omar Khayyam introduced a new calendar. The length of the year was measured as 365.24219858156 days and is very accurate. It didn’t catch on in the West.

https://www.britannica.com/biography/Omar-Khayyam-Persian-poet-and-astronomer

Omar Khayyam


https://www.timeanddate.com/calendar/persian-calendar.html

Marathon

One of the important battles in the wars between the Greeks and Persians took place on the Plains of Marathon. Herodotus tells about how in 490 bc, when the Greeks were seriously outnumbered, a messenger named Pheidippides (Fay DIP e deez) ran from Athens to Sparta to get their help. Then he ran to Marathon to join the fight, THEN ran back to Athens to tell everybody that the Greeks won.

Around the world we still celebrate Pheidippides’ heroic run in races called marathons. If you run a marathon, it’s 26 miles and 385 yards—the distance from the Plains of Marathon to Athens. The very fastest runners have done it in a little over 2 hours!

Herodotus of Halicarnassus

Herodotus reading his Histories to the crowd

“These are the researches of Herodotus of Halicarnassus, which he publishes, in the hope of thereby preserving from decay the remembrance of what men have done, and of preventing the great and wonderful actions of the Greeks and the Barbarians from losing their due meed of glory; and withal to put on record what were their grounds of feuds.”

While the Greeks did think of time as a cycle, there was still a desire to reach back in time to remember stories from the past. We saw how Homer kept alive the story of the siege of Troy through his epic poem, the Iliad.

Herodotus (Hay ROD oh toos) was a Greek who lived in the fourth century bc and is thought to be the first historian. He wrote The Histories mostly about the wars between the Greeks and Persians and how they got started. Herodotus was a great storyteller, but what made him a historian is that he investigated, he did research—he got his information from several sources; he visited the places where the history took place; he went to the library; he interviewed people—then he arranged the information he’d gathered to explain how and why something happened.

I have a paperback copy of The Histories. It’s not an easy read, but I like to ‘dip into’ my copy and read whatever I open to. The battle of Thermopylae is in there—that story has since been made into a graphic novel and movie, The 300—and the battles of Marathon and Salamis. Herodotus included lots of oddball side-stories and observations, which are also fun. The Persian emperors Cyrus, Darius and Xerxes are in there (Xerxes is thought to be the party-boy king Ahasuerus from the biblical Book of Esther).

History is often about the big military battles and wars. I want this history, the one you’re reading right now, to be about ideas. But I’m telling you, if the Greeks hadn’t broken the will of the mighty Persian Empire and eventually beat ‘em, there would have been no flowering of art, literature, philosophy and democracy that happened after the wars—and was the Greeks’ gift to us.

Back to the beginning of The Western Civ User’s Guide to Time & Space

Daniel

Continuing our everything-you-need-to-know-about-the Major-Prophets series, here’s Daniel.

Daniel lived to see the end of the Babylonian empire and the rise of the Persian empire—directly serving Emperors Nebuchadnezzar, Belshazzar and Darius. From Daniel we get expressions like ‘feet of clay’ and ‘the handwriting on the wall’ (do people still say that?) As a girl my mom learned to remember Daniel’s pals Shadrach, Meshach and Abednego by memorizing ‘Shake a bed, make a bed, and to bed we go’, so I pass it along. The Larks have a pretty snappy take on the story. Here’s Satchmo’s version. ‘Seven times hotter, hotter than it oughta be!’

 

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