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Andromeda galaxy

The astronomer Abdou al-Rahman al-Sufi, also known as Azophi, reported the first observation of a group of stars outside of the milky way , the Andromeda galaxy in 964. He described this in his ‘Book of Fixed Stars’ published the same year.

In addition to that, to improve the work of Ptolemy, ‘Almagest’ and to account for the procession of the stars, he added a three leveled scale to measure the magnitude of the stars which increased the accuracy of the measurements of their positions. Moreover, his observation of the inclination of the ecliptic plane compared to the celestial equator was important and lead to an accurate measurement of the tropical year.

Even though the ‘Book of Fixed Stars’ is important in the history of astronomy, the first English translation appeared only in 2010, a thousand years after its original date of publishing.

Written by: Fatma Abdi.