Solar disk radius measured by Solar occultation by the Moon using bolometric and photometric instruments on board the PICARD satellite

摘要

1. Scientific rational The solar disk radius is a basic metrological quantity as the planet's radius of the solar system. Despite the importance of having an accurate value of the solar disk radius, the existing measurements show differences likely due to large uncertainties due to the use of different measurement techniques, instrument calibration (if any), wavelength domain of measurements, and atmospheric effects for instruments running from the ground. Furthermore, is the solar radius constant or changing with time in particular with solar activity? The solar radius value depends on the solar atmosphere opacity, which allows solar model validation by comparing model predictions with the observations.