arzachel

Updated: June 9, 2025

Then leaving Pitatus to the right, on the 30th degree, it went along the south of the Sea of Clouds, of which it had already approached the north. Different amphitheatres appeared confusedly under the white light of the full moon Bouillaud, Purbach, almost square with a central crater, then Arzachel, whose interior mountain shone with indefinable brilliancy.

Jules Verne - The Moon-Voyage

Meanwhile the Moors were leaders of science in the west, and Arzachel of Toledo improved the solar tables very much. Ulugh Begh, grandson of the great Tamerlane the Tartar, built a fine observatory at Samarcand in the fifteenth century, and made a great catalogue of stars, the first since the time of Hipparchus. Nicolai Copernicus, a Sclav, was born in 1473 at Thorn, in Polish Prussia.

George Forbes - History of Astronomy

Arzachel explained this supposed phenomenon by assuming that the equinoctial points, or the points of intersection of the equator and the ecliptic, revolve in circles of eight degrees' radius. The first points of Aries and Libra were supposed to describe the circumference of these circles in about eight hundred years.

Edward Huntington Williams - A History of Science — Volume 2

In the eleventh century another Arabian discoverer, Arzachel, observing the sun to be less advanced than Albategnius had found it, inferred incorrectly that the sun had receded in the mean time. The modern explanation of this observation is that the measurement of Albategnius was somewhat in error, since we know that the sun's motion is steadily progressive.

Edward Huntington Williams - A History of Science — Volume 2