Welcome to the biography of Dominique Fran?ois Jean Arago, a distinguished figure whose life and work left an indelible mark on the scientific landscape of his time and beyond. As the one-time Director of the Paris Observatory, Arago's contributions to astronomy and physics resonate through the annals of scientific history. In this comprehensive account, we delve into the multifaceted persona of Arago, exploring not only his ground-breaking scientific achievements but also the broader context of his era. From the vibrant scientific environment of 19th-century France to Arago's pivotal role in advancing our understanding of light's velocity, electromagnetic phenomena, and the dimensions of the Earth, each chapter unveils a new facet of his remarkable journey. Throughout these pages, Arago emerges not only as a brilliant astronomer and physicist but also as a tireless advocate for the advancement of science and the dissemination of knowledge. His legacy continues to inspire generations of scientists, reminding us of the transformative power of curiosity and intellect.