What Is a Sphere in the Eyes of Islamic Mathematicians? (Children)

Although Islamic mathematicians used different expressions to define the sphere, they all described the same concept. Below are some important important scientists’ explanations of the sphere:

• Al-Khwarizmi defined the sphere as: "A sphere is a round solid formed by lines extending from a point called the center to the surface, all of equal length."
• Al-Biruni described it as: "A sphere is a round solid bounded by a single surface, where all lines drawn from the surface to the center are equal."
• Ali Kuşçu provided a detailed description: "A sphere is a three-dimensional solid enclosed by a round surface. All lines drawn from an internal point (the center) to this surface are equal. These lines are called radii. A line passing through the center and connecting two opposite points on the sphere is called the diameter. If the sphere is rotated around this diameter, the diameter becomes the axis and its two ends become the poles."

Sphere Knowledge in Islamic Astronomy

The Sky and the Use of the Sphere

Islamic mathematicians derived their knowledge of the sphere from ancient Greek scientists Euclid and Archimedes. Using this knowledge, they studied astronomy (the science of the sky) and spherical triangles (triangles drawn on the surface of a sphere). The sky was conceived as a sphere with Earth at its center, and stars were assumed to be fixed on its surface like.

Earth and Sky: Mathematics and Astronomy

Celestial Spheres and Instruments

In earlier times, instruments shaped as spheres were constructed to understand the sky. Some of these include:

• Celestial Sphere: A model designed to show the positions of stars in the sky.
• Ring Sphere: Used to study the movements of celestial bodies; various measurements could be made with this instrument.
• Astrolabe: An instrument used to determine the positions of stars in the sky. Famous scientists in the Ottoman Empire, such as Taqi al-Din, constructed such devices.

Celestial Spheres and Astronomical Instruments

The Terrestrial Sphere and Other Uses

Geographers, in addition to astronomers, also used the sphere. The terrestrial sphere is a model representing the map of Earth. Moreover, opticians used glass spheres called "burning spheres" to focus sunlight to a single point.

Science and the Sky: Astronomical Spheres

Why the Sphere?

The sphere proved to be a crucial model for understanding both the sky and the Earth. Thanks to these instruments, the movements of the sky, the positions of planets, and the structure of Earth were better understood. Islamic mathematicians and scientists took significant steps in this field, paving the way for future generations of scientists path.

Islamic Mathematicians’ Celestial Sphere Models