From the Inside of the Sun to its Atmosphere

Charles Greeley Abbot was correct in predicting the solar constant is decidedly inconstant. Indeed, the solar irradiance exhibits pronounced variations on nearly all currently accessible observational time scales. There is overwhelming evidence for a tight correlation between the Sun's magnetic activity cycle and broadband spectral irradiance in the sense that greater magnetic activity implies excess irradiance and vice-versa. Global dynamical and evolutionary processes determine the time-averaged solar luminosity. In this realm the variable magnetic field is of no consequence. It is therefore of interest to ask how deep within the solar envelope and interior do the irradiance fluctuations persist, and from where do they originate. Observational and theoretical evidence will be presented to suggest that an answer to this fundamental question may soon be in hand.