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Egyptians built the Nabta Playa stone circle, believed to mark the summer solstice.
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The Great Pyramid of Giza was aligned with the North Star. -
Babylonians divided the sky into zones and recorded early appearances of Halley’s Comet. -
Babylonians began documenting the sun and moon’s movements daily, monthly, and yearly. -
Greek philosopher Pythagoras proposed that the Earth is spherical. -
Chinese astronomer Gan De observed Ganymede, describing it as a small reddish “star” near Jupiter. -
Eratosthenes accurately calculated Earth’s circumference and axis tilt, creating the leap-day concept. -
Aryabhata proposed that the Earth rotates on its axis
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Aryabhata discovered that the Moon and planets shine by reflected sunlight.
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Mayan astronomers used shadow-casting devices to track celestial motion. -
From these observations, they developed the Mayan Calendar to measure time. -
The Dunhuang Star Atlas was created it is the oldest preserved star map known. -
Persian astronomer al-Sufi described the Andromeda Galaxy in The Book of Fixed Stars. -
Al-Khujandi built a giant sextant to measure Earth’s axis tilt with great precision.