This chapter explores the scientific journey behind understanding why the sky is blue, beginning with John Tyndall’s pioneering experiments on light scattering and culminating in Lord Rayleigh’s theoretical framework grounded in Maxwell’s equations. It introduces the Tyndall effect and explains how Rayleigh scattering by air molecules accounts for the blue hue of the sky. The discussion then transitions into modern applications of light scattering in biology, particularly the challenges posed by the small size and low scattering efficiency of biomolecules. To overcome these limitations, the chapter presents three biophotonics strategies: (1) using scattering markers like DNA-tethered beads to produce detectable signals, (2) employing advanced image processing techniques to detect and study proteins without labels, and (3) amplifying weak scattering through cavity-based interferometric techniques. These methods enable sensitive analysis of protein behavior and interactions, crucial for advancing fields like drug discovery and precision medicine. The chapter illustrates how foundational physics informs state-of-the-art biological measurements, and how innovations in light manipulation continue to push the boundaries of what we can observe in the molecular world.