# Who else measured the circumference of the Earth in the Antiquity?

The first famous measurement of the Earth's circumference was made by Eratosthenes. But he wasn't the only one to carry out this measurement. For instance Posidonius provided the estimate of the circumference that was used by Christopher Columbus. Did other people provide other estimates during the Antiquity?

• Posidonius en.wikipedia.org/wiki/… but his works did not survive. They are known from secondary sources. Jun 4, 2021 at 18:38
• @AlexandreEremenko. The works of Eratosthenes are also lost. So what is the point?
– fdb
Jun 10, 2021 at 12:58
• @fdb: the point is that I answered the question: "who else measured...". Jun 10, 2021 at 14:27
• @AlexandreEremenko. Fair enough.
– fdb
Jun 10, 2021 at 14:43
• @AlexandreEremenko I do mention Posidonius in the question, so you don't quite answer the question. Jun 11, 2021 at 6:26

I don't know if it counts as "the Antiquity", but medievalMuslim scholars did also calulate the circumference of Earth.

This paper about Al-Biruni (973->1050) says:

In fact, it was long before Al-Biruni’s time that Muslim scholars started their researches on mathematical geography and geodesy. A success obtained by them was the measurement of the meridian arc, measurement made by astronomers of Caliph Al-Mamun. From this measure, Earth’s circumference had been deduced and compared to the value given by ancient Greeks. Al-Biruni, eager to find his own value, proposed a new method based on sine trigonometric functions. Using it, he measured the Earth’s circumference finding a value quite close to the modern one.

Al-Ma'mun was born in 786 and reigned from 813-833.

Al-Ma'mun conducted, in the plains of Mesopotamia, two astronomical operations intended to achieve a degree measurement (al-Ma'mun's arc measurement). The crater Almanon on the moon is named in recognition of his contributions to astronomy.