Astrology has a long history, stretching back thousands of years and permeating across numerous ancient civilizations. In modern times, astrology is big business — and it's growing. In 2025, the industry was estimated to be worth around $3 billion . In this excerpt from " What Science Says About Astrology " (Columbia University Press, 2026), author and science journalist Carlos Orsi looks at a study of 20 million people that sought to test whether star signs have a role in romantic compatibility. The most robust use of data to test astrology is the study of love signs conducted by David Voas in 2007, involving data from more than 20 million people from the 2001 census from England and Wales. Voas tested the hypothesis that certain sun signs were "more compatible" for romantic relationships. The use of the supposed romantic compatibility/incompatibility between signs or planetary configurations to test astrology's validity has a long history.…