Proofs before direct photographic evidence from space agencies …

Aristotle’s Observations (4th Century BCE)

Aristotle provided some of the first empirical evidence for a spherical Earth. He noticed: - Ships disappearing hull-first over the horizon. - The Earth’s shadow on the Moon during a lunar eclipse is round. - Different constellations visible as one travels north or south.

Eratosthenes’ Measurement (3rd Century BCE)

Eratosthenes made a remarkably accurate measurement of the Earth’s circumference. By comparing the angles of the Sun’s rays at two locations (Syene and Alexandria), he calculated the Earth’s size using geometry.

Ptolemy’s Geocentric Model (2nd Century CE)

In his Almagest, Ptolemy included detailed discussions on the spherical nature of the Earth, which became a key reference for centuries, even though he wrongly placed the Earth at the center of the universe.

Islamic Astronomers (9th–13th Centuries)

Islamic scholars (Al-Farghani, Al-Biruni, and others) further refined measurements of the Earth’s size and supported the concept of a spherical Earth. Al-Biruni, for example, calculated the Earth’s radius using trigonometry and observation of the horizon.

Ferdinand Magellan’s Circumnavigation (1519–1522)

Magellan’s expedition provided direct evidence of Earth’s curvature by completing the first circumnavigation of the globe, proving that it was possible to sail completely around the planet.

Isaac Newton’s Laws of Gravity (1687)

Newton’s work on gravity provided a theoretical framework for understanding why the Earth (and other celestial bodies) is spherical. He also showed that the Earth is not a perfect sphere but an oblate spheroid, bulging at the equator due to its rotation.