It is He Who hath created for you all things that are on earth; Moreover His design comprehended the heavens, for He gave order and perfection...
(Turkiye 858 - Iraq 929)
He is known as a Muslim, Astronomer and Mathematician who invented Trigonometry in Mathematics about 1000 years ago. He calculated the rotation of the moon around the sun as 365 days, 5 hours, 48 minutes, 24 seconds. Today, this is calculated as 365 days, 5 hours, 48 minutes and 46 seconds. So Battani was wrong by 22 seconds.
Some of Bettanî's other important discoveries and achievements are as follows: The determination of the average motion of the moon in longitude, the measurement of the apparent diameters of the sun and the moon and the variation of the sun's diameter over the course of a year and the moon's over the course of an anomalous month, the conclusion from these discoveries that an annular eclipse of the sun, which Ptolemy said was impossible, was possible, and the development of a very robust method for calculating the degree of lunar eclipse.