Ancient Astronomy

As the oldest science, astronomy has a rich history that extends back to ancient times. It is surprising to consider what ancient astronomers already knew. In fact, they not only knew the earth was a sphere, but the ancient scientist Eratosthenes had measured the circumference of the Earth with great precision. Watch the famous astronomer Carl Sagan explain how Eratosthenes used shadows to make his measurement in the video Carl Sagan - Eratosthenes.
One of the greatest scientific challenges for ancient astronomers was explaining the motion of the planets in our night sky. To appreciate just how bizarre this motion really is, watch the video The Wandering Planets.
Explore 2.2 Ancient Astronomy to learn how the ancient Greeks’ observations and theories laid the groundwork for modern astronomy, despite their geocentric view.
Ptolemy’s model of the solar system was complicated, but it did explain the unusual motion of the planets quite accurately. Check out the teacher video Ptolemaic System Simulator to see exactly how the model works. If you like, you can also experiment with the simulation for yourself.
Read 2.3 Astrology and Astronomy to differentiate between the ancient practice of astrology and the scientific foundation of astronomy, highlighting astrology’s historical context and its distinction from empirical science.
The “signs of the zodiac” are simply the twelve constellations that the sun passes through during its annual motion around the celestial sphere (a path that astronomers call the “ecliptic”). Use the Zodiac Simulator to see how the sun’s position in the sky changes relative to the background stars (and the zodiac constellations) over the course of a year.
Watch Astrology and the Star of Bethlehem to see an astronomical view of one of history’s most famous astrological events.
I love encountering examples of astronomy in popular movies and video games. One of the best examples I’ve seen in recent years was in the Harry Potter-inspired video game “Hogwart’s Legacy.” This game includes real constellations, telescope observations, and even a spicy astronomy professor who complains about astrology. Check out my video Astronomy in Hogwarts Legacy to see highlights from the game.
The “Big Bang Theory” was a popular TV comedy show in the mid-2010’s. Its main characters were Ph.D. scientists at the elite CalTech University. The show stands out to me for the remarkable accuracy of the scientific dialogue. Watch this brief clip where the main characters meet for the first time, and Sheldon Debunks Astrology.
If you learn nothing else from this entire course, please remember that you took a course in “Astronomy” and not “Astrology.” :)