On the Constancy of the Solar Diameter. II.

Abstract

The Michelson Doppler Imager instrument on board SOHO has operated for most of a solar cycle. Here we present a careful analysis of solar astrometric data obtained with it from above the Earth's turbulent atmosphere. These data yield the most accurate direct constraint on possible solar radius variations on timescales from minutes to years and the first accurate determination of the solar radius obtained in the absence of atmospheric seeing.