History of science
The history of science traces how scientific ideas were born, contested and ultimately prevailed. Orb: On the Movements of the Earth unfolds at a turning point: the shift from geocentrism to heliocentrism, and the price paid by those who dared to observe the sky differently.
Entries in this discipline
Aristotelian physics
Rafal cites Aristotle to prove the Earth is at the center in Orb. We explain Aristotelian physics and its link to geocentrism.
The astrolabe
In Orb: On the Movements of the Earth, Rafal owns an astrolabe. We explain what this ancient astronomical instrument is, what it does and how it works.
Ptolemy's geocentric model
Before heliocentrism, the Earth sat at the center of the world. We explain Ptolemy's geocentric model, its epicycles, and why it lasted over a thousand years.
Heliocentrism
Hubert defends a forbidden idea in Orb: the Sun at the center, the Earth turning. We explain heliocentrism, its history, and why it caused such an uproar.
Star magnitude
Rafal marvels at seeing a magnitude-six star in Orb. We explain what magnitude is, why the scale runs backwards, and the limit of the naked eye.
Why measure a star with an astrolabe
The stars are already engraved on the astrolabe, so why sight one? The instrument is a calculator that derives the time, your orientation and your latitude.