Ibnu Yunus- the scientist whose create the watch

Ibn Yunus

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Ibn Yunus (Arabic: ابن يونس) (full name, Abu al-Hasan 'Ali abi Sa'id 'Abd al-Rahman ibn Ahmad ibn Yunus al-Sadafi al-Misri) (c. 950-1009) was an important Egyptian Muslim astronomer and mathematician,^[1][2][3][4] whose works are noted for being ahead of their time, having been based on almost modern-like meticulous calculations and attention to detail.

The Ibn Yunus crater, on the Moon, is named after him.

Works

[Astrology

In astrology, noted for making predictions and having written the Kitab bulugh al-umniyya ("On the Attainment of Desire"), a work concerning the heliacal risings of Sirius, and on predictions concerning what day of the week the Coptic year will start on.

[Astronomy

Ibn Yunus' most famous work in Islamic astronomy, al-Zij al-Kabir al-Hakimi (c. 1000 AD), was a handbook of astronomical tables which contained very accurate observations, many of which may have been obtained with very large astronomical instruments. According to N. M. Swerdlow, the Zij al-Kabir al-Hakimi is "a work of outstanding originality of which just over half survives".^[7]

Ibn Yunus described 40 planetary conjunctions and 30 lunar eclipses. For example, he accurately describes the planetary conjunction that occurred in the year 1000 AD as follows:^[8]

"A conjunction of Venus and Mercury in Gemini, observed in the western sky: The two planets were in conjunction after sunset on the night [of Sunday 19 May 1000]. The time was approximately eight equinoctial hours after midday on Sunday ... . Mercury was north of Venus and their latitude difference was a third of a degree."

Modern knowledge of the positions of the planets confirms that his description and his calculation of the distance being one third of a degree is exactly correct. In the 19th century, Simon Newcomb found Ibn Yunus' observations on conjunctions and eclipses reliable enough to use them in his lunar theory to determine the secular acceleration of the moon.^[8][9] Ibn Yunus' other observations also inspired Laplace's Obliquity of the Ecliptic and Inequalities of Jupiter and Saturn's. Ibn Yunus also observed more than 10,000 entries for the sun's position for many years using a large monumental astrolabe with a diameter of nearly 1.4 metres.^[9]

[Poetry

Ibn Yunus is also thought to have been an Arabic poet, and to have used very large instruments in making his observations, though neither assertion is certain.

[Other works

He is said to have predicted his own death, seven days prior to the event, and without any outward sign of ill health.

Ibn Yunus is believed to have described an early type of pendulum in the 10th century.He used it for making measurements of time, like a pendulum clock.^[10][11]

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