Abu Sahl al-Quhi facts for kids

Abū Sahl Wayjan ibn Rustam al-Kūhī (al-Qūhī; Persian: ابوسهل بیژن کوهی Abusahl Bijan-e Koohi) was a super smart Persian scientist. He lived during a special time called the Islamic Golden Age, around the 10th century. He was an amazing mathematician, physicist, and astronomer. He was born in Amol and became famous in Baghdad.

Meet Abu Sahl al-Quhi: A Genius of the Past

A Brilliant Mind from the Islamic Golden Age

Al-Qūhī came from a place called Kuh in Tabaristan. He lived and worked in Baghdad, a very important city for learning back then. He is known as one of the greatest geometers. A geometer is someone who studies shapes, sizes, and positions of figures. He wrote many important books about math and space.

Master of Math and Geometry

Al-Qūhī loved to solve tough math problems. He focused on problems that were even harder than what famous Greek mathematicians like Archimedes and Apollonius of Perga worked on. These problems often led to very complex equations.

For example, he figured out how to draw a perfect five-sided shape (an equilateral pentagon) inside a square. This problem needed a very advanced type of equation to solve.

The Perfect Compass

An old drawing of al-Qūhī's perfect compass. It helped draw many shapes!

Al-Qūhī also wrote about a special tool he might have invented. He called it the "perfect compass." This wasn't just any compass. It had a leg that could change its length. This amazing compass could draw all sorts of shapes. It could draw straight lines, circles, and even more complex shapes called conic sections. Conic sections include ellipses (like stretched circles), parabolas (like the path of a thrown ball), and hyperbolas.

Stargazer and Observatory Leader

Al-Qūhī was also a leading astronomer. In the year 988 AD, he was in charge of an important observatory. This observatory was built in Baghdad by a ruler named Sharaf al-Dawla. An observatory is a place where scientists watch and study the stars and planets. Al-Qūhī also wrote a detailed book about the astrolabe. An astrolabe was a very old tool used to find the positions of stars and planets.

Ideas About Gravity

Al-Qūhī even had ideas about weight and gravity. Like the ancient Greek thinker Aristotle, al-Qūhī thought that how heavy something felt depended on how far it was from the center of the Earth. This was an early way of thinking about how gravity works.

Keeping in Touch

We know a lot about al-Qūhī's work because some of his letters were saved. He wrote to a high-ranking government official named Abu Ishaq al-Sabi. This official was also very interested in mathematics. Their letters help us understand al-Qūhī's brilliant ideas.