Astronomical study of an Armiliary sphere , a model of objects in the sky, comprising a framework of brass rings centred on Earth, and; a celestial map [right], showing the seven planets, represented via concentric circles of different colours, and the signs of the zodiac around the outer edge. Unnumbered plate from Jihannuma (loosely translated as Displaying the World) by Katip Çelebi (ed. by Ibrahim Müteferrika, Constantinople, 1732). Katip Çelebi (كاتب جلبي), or Ḥājjī Khalīfa (حاجي خليفة) (1609-1657) was an Ottoman-Turkish scholar, historian and geographer. Jihannuma is a world atlas containing maps of earth and the stars. It strove to offer proofs that the earth was round, arguing against the widespread view in the Islamic world at the time, which claimed that the earth was flat. Mughal Library