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The Great Pyramid of Giza was built to align precisely with the North Star (then Thuban), showing advanced knowledge of star positions.
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Egyptians developed a solar calendar of 12 months, 30 days each, with 5 festival days a precursor to the modern calendar system.
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The Babylonians began documenting the daily, monthly, and yearly positions of the Sun and Moon among the earliest systematic astronomical records.
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They divided the sky into regions (similar to our constellations today), laying groundwork for celestial mapping.
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Observing ships disappearing over the horizon, Pythagoras theorized that Earth was round — a revolutionary idea for its time.
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Gan De recorded seeing a small reddish “star” near Jupiter — the earliest known observation of one of its moons
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Using shadows in Syene and Alexandria, he calculated Earth’s circumference with remarkable accuracy (within a few hundred miles).
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The Mayans created a precise calendar based on solar and planetary cycles to track time and predict celestial events.
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Aryabhata suggested that Earth rotates on its axis, explaining the apparent movement of stars and the Sun.
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Aryabhata recognized that the Moon and planets shine because they reflect sunlight — a fundamental concept in modern astronomy.
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The oldest known preserved star map, showing detailed constellations and celestial coordinates used for navigation and study.
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They invented instruments to study shadows cast by the Sun, improving their understanding of solstices and equinoxes.
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In The Book of Fixed Stars, Al-Sufi documented the Andromeda Galaxy — the first recorded observation of another galaxy.
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Abu Mahmud al-Khujandi created a massive sextant to measure Earth’s axial tilt with a precision only 2 minutes off modern values.