Menelaus of Alexandria facts for kids

Menelaus of Alexandria was an important Greek mathematician and astronomer. He lived around 70 to 140 CE. He was the first to understand that geodesics (the shortest path between two points on a curved surface) are like straight lines on a flat surface.

Who Was Menelaus of Alexandria?

Sphaericorum libri tres (Three Books on Spherical Objects)

Very little is known about Menelaus's life. It is thought that he lived in Rome. He probably moved there after spending his youth in Alexandria. Other ancient writers, like Pappus of Alexandria and Proclus, called him "Menelaus of Alexandria." The writer Plutarch even recorded a conversation Menelaus had in Rome.

His Astronomical Observations

The famous astronomer Ptolemy (who lived in the 2nd century CE) wrote about Menelaus. In his work Almagest, Ptolemy mentioned two important observations Menelaus made. These happened in Rome in January of the year 98 CE.

Menelaus observed the Moon passing in front of two bright stars. These stars were Spica and Beta Scorpii. Ptolemy used these observations to confirm something called precession of the equinoxes. This is a slow wobble of Earth's axis. This phenomenon had been discovered much earlier by another astronomer named Hipparchus.

What Was His Main Work?

In a 10th-century book called Kitāb al-Fihrist, six books by Menelaus are mentioned. These included books on geometry and triangles. However, only one of his books still exists today. This book is called Sphaerica, and it is available in Arabic translation.

Sphaerica has three parts. It talks about the geometry of a sphere. This means it explains shapes and measurements on a curved surface, like a ball. It also shows how this geometry is used in astronomy. For example, it helps with measuring and calculating things in space.

In this book, Menelaus introduced the idea of a spherical triangle. These are shapes made of three curved lines on a sphere. He called them "trilaterals." He also proved Menelaus' theorem. This theorem is about points that lie on a straight line along the edges of a triangle. He also proved a similar theorem for spherical triangles. Later, in the 16th century, the astronomer Francesco Maurolico translated this important work.

His Legacy

The lunar crater Menelaus on the Moon is named after him. This is a way to honor his important contributions to mathematics and astronomy.

See also

In Spanish: Menelao de Alejandría para niños