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How did Posidonius calculate the circumference of the Earth?
What was Posidonius' equatorial circumference?
Did Posidonius see Canopus above the horizon?
What if Posidonius used an Egyptian astronomer?
How many stadia did Posidonius calculate?
What was Posidonius theory?
Earth's circumference is the distance around Earth. Measured around the equator, it is 40,075.017 km (24,901.461 mi). Measured passing through the poles, the circumference is 40,007.863 km (24,859.734 mi). Measurement of Earth's circumference has been important to navigation since ancient times.
Posidonius calculated the Earth's circumference by the arc measurement method, by reference to the position of the star Canopus. As explained by Cleomedes, Posidonius observed Canopus on but never above the horizon at Rhodes, while at Alexandria he saw it ascend as far as 7½ degrees above the horizon (the meridian arc between the latitude of ...
Posidonius calculated the Earth's circumference by observing the position of the bright star Canopus. He observed that the star could be viewed on, but never above, the horizon at Rhodes, while at Alexandria he saw it emerge clearly above the horizon.
The procedure is to find the circumference of the earth at about 180,000 stades. difference in latitude between two places on the same meridian, measure the terrestrial distance between these places, and thus find the measure of 10 and of the whole circumference.
A century after Eratosthenes, the Greek astronomer Posidonius of Rhodes (c. 135–51 BCE) calculated the Earth’s circumference. Posidonius used the star Canopus as frame of reference: when the star is visible at the horizon in Rhodes, it is 7.5 degrees above the horizon in Alexandria.
- The concept of the spherical earth was gradually accepted during the Middle Ages (before the Renaissance) - at least among the more educated member...
- While the well being at a spot where the shadow was negligible was convenient, he could have used two sticks a known north/south distance apart (ea...
- While stars move, their patterns will remain the same. And that's how we have constellations!
- Those are equatorial measurements. If you measure the circumference in the direction Eratosthenes did, which is north to south, the distance is les...
- i agree the greeks just were stubborn and didn't want to believe that or the information wasn't passed on to the greeks
May 1, 2017 · Posidonius attempted to calculate the circumference of the Earth by assuming the cities of Rhodes (Greece) and Alexandria (Egypt) were on the same meridian. He also thought that the star Canopus touched the horizon at Rhodes at a meridian altitude of 7 30' or V48 of the circumference of a circle at Alexandria.
Posidonius used the stars to determine the earth's circumference. He observed that a given star could be seen just on the horizon at Rhodes. He then measured the star's elevation at Alexandria, Egypt, and calculated the angle of difference to be 7.5 degrees or 1/48th of a circle.
