Ibn Yunus facts for kids
Ibn Yunus (full name: Abu al-Hasan 'Ali ibn 'Abd al-Rahman ibn Ahmad ibn Yunus al-Sadafi al-Misri) was a very important Egyptian astronomer and mathematician. He lived from about 950 to 1009. His work was very advanced for his time. He was known for his careful calculations and attention to detail.
A crater on the Moon is named Ibn Yunus after him.
Contents
Life of Ibn Yunus
We don't know much about Ibn Yunus's early life or how he was educated. He was born in Egypt between 950 and 952. His family was well-respected in the city of Fustat.
His father was a historian and a scholar. He wrote two books about the history of Egypt. One was about the people of Egypt. The other was based on what travelers said about Egypt. Ibn Yunus's father was known as "Egypt's most famous early historian."
When Ibn Yunus was young, the Fatimid family came to power. They founded a new city called Cairo. Ibn Yunus worked as an astronomer for the Fatimid rulers for 26 years. He worked first for Caliph al-Aziz and then for al-Hakim. He dedicated his most famous astronomy book, al-Zij al-Kabir al-Hakimi, to al-Hakim.
Besides his math skills, Ibn Yunus was also known for being a bit unusual and for writing poetry.
Ibn Yunus's Works
Astrology and Predictions
Ibn Yunus also worked in astrology. This is the study of how the positions of stars and planets might affect events on Earth. He was known for making predictions.
He wrote a book called Kitab bulugh al-umniyya. This book was about the heliacal risings of Sirius. This is when the star Sirius first becomes visible in the morning sky. He also made predictions about which day of the week the Coptic year would start on.
Astronomy and Observations
Ibn Yunus's most famous work was in Islamic astronomy. It was called al-Zij al-Kabir al-Hakimi. This book was written around the year 1000. It was a guide filled with astronomical tables. These tables contained very accurate observations of the sky. He might have used very large tools to make these observations.
A historian named N. M. Swerdlow said that al-Zij al-Kabir al-Hakimi was "a work of outstanding originality." This means it was very new and clever. About half of the book still exists today.
Ibn Yunus described 40 times when planets came close together (called planetary conjunctions). He also described 30 lunar eclipses. For example, he accurately described a planetary conjunction in the year 1000. He wrote:
- 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.
Today, we know that his description and his calculation of the distance between the planets were exactly right. Ibn Yunus's observations of conjunctions and eclipses were used by later scientists. These scientists, like Richard Dunthorne and Simon Newcomb, used his work to study how the moon's speed changes over time.
See also
In Spanish: Ibn Yunus para niños
