How Eclipses Demonstrated Our Solar System
Summary
Hosts of PBS Space Time explore how ancient and early modern astronomers used eclipses and transits to map the solar system. The episode details how the Greeks, including Anaxagoras and Aristarchus, deduced the relative sizes and distances of the Earth, Moon, and Sun using shadow geometry. It also covers Eratosthenes' calculation of Earth's radius and Edmund Halley's proposal to measure the astronomical unit via the 1761 and 1769 transits of Venus.
Topics discussed
Sponsors and introduction to the upcoming solar eclipse
The visceral nature of eclipses and the path to scientific understanding
Ancient Greek knowledge of Earth's roundness via eclipses
Anaxagoras and the geometry of solar and lunar eclipses
Sponsor breaks and transition to Aristarchus of Samos
Using lunar phase durations to estimate the Sun's distance
Aristarchus' calculations of relative sizes and distances
Eratosthenes and the measurement of Earth's radius
Kepler's laws and the need for the astronomical unit
Measuring solar parallax via the transit of Venus
The success of the 1769 transit observations and PBS Earth Month
Sponsor breaks and Space Time eclipse merch announcement
Patreon support, LinkedIn, and McDonald's advertisements
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