stronomy in medieval Islam and Islamic cosmology

In the 11th century, the Andalusian astronomer Arzachel hypothesized that the orbits of the planets are elliptic orbits, rather than circular orbits.^[25] In the 11th century, the transit of Venus was observed by Avicenna, who established that Venus was, at least sometimes, below the Sun.^[26] In the 12th century, Ibn Bajjah observed "two planets as black spots on the face of the Sun," which was later identified as the transit of Mercury and Venus by the Maragha astronomer Qotb al-Din Shirazi in the 13th century.