Final answer:
The calculation of the circumference of the Earth was one of the most significant discoveries made by Muslims during the rise of power throughout Europe and the Middle East.
Step-by-step explanation:
One of the most significant discoveries made by Muslims during the rise of power throughout Europe and the Middle East was the calculation of the circumference of the Earth. During the 830s, astronomers working for caliph al-Ma'mun improved on ancient measurements and established accurate figures for the circumference of the Earth. This discovery had important implications for navigation and mapmaking.