astronomy

Astronomy, astrophysics and cosmology: what is the difference?

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The three words are often used interchangeably, and the boundaries really are blurry. Still, each has a distinct emphasis. Astronomy: observing the sky Astronomy is the oldest of the natural sciences. It studies everything beyond Earth’s atmosphere: planets, stars, galaxies and more. Historically, it focused on measuring and observing: positions, motions, brightness and distances. Ancient … Read more

What is the history of astronomy?

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Astronomy is probably the oldest science. People watched the sky to keep time, plan harvests, navigate and make sense of their place in the world long before writing existed. Ancient skywatchers Greek models Greek thinkers sought geometric explanations. Eratosthenes estimated Earth’s circumference around 240 BCE. Aristarchus proposed that Earth orbits the Sun, but the Earth-centered … Read more