Welcome back to the FQxI "My Favourite" series, where our members explore their most cherished scientific ideas. In episode three, Julian Babrour takes us back to 150 BC to uncover the revolutionary insights of Hipparchus, the great ancient astronomer. Hipparchus developed one of the first dynamical equations to describe the Sun's motion across the ecliptic, laying the foundation for the entire field of dynamics. He introduced the concept of relating time to the Sun’s position, relying on precise ratios and geometric reasoning. This theory explained the non-uniformity in the Sun's motion and established a paradigm that has helped shape physics for millennia. Hipparchus’s legacy reminds us of the deep connections between observation, mathematics, and the quest to understand the cosmos. Support FQxI Help us continue to explore and share foundational scientific ideas. Your donation makes a difference: https://fqxi.org/support-our-work/don... Stay tuned for the next episode, where another FQxI member shares their favourite scientific inspiration.