Because telescopic observation of solar behaviour is limited only to the past four centuries, it remains uncertain whether the Sun has been relatively quiescent during the past 4.5 billion years or has exhibited significant variability in activity. Such study requires inquiry into terrestrial records, meteorites, the Moon, and proxy observations of solar-like stars, from young pre-main sequence stars to those of an age and chemical composition similar to the Sun. This volume examines the subject through an interdisciplinary approach to solar physics, as 89 contributors trace the evolution of the Sun and provide a review of our current understanding of both its structure and its role in the origin and evolution of the solar system. Of particular interest are a new perspective on the historic record of sunspot observation, the final establishment of the absolute irradiance variability of the Sun, and coverage of the question of variability in solar diameter, along with related theory. While research on solar variability tends to be specialized, The Sun in Time consolidates current knowledge of solar evolution gained from the variety of these approaches.