The size and the shape of the Sun: Do they vary?, Prof. Jeffrey Kuhn (University of Hawaii)

Knowledge of the Sun's shape has been used to test theories of gravity while its
*apparent* variability is sensitive to the mechanisms that cause the thus far unexplained
11-year solar cycle. Solar astrometry from space became possible more than a decade
ago with a satellite called SOHO but recently with a new experiment called the Helio-
seismic and Magnetic Imager onboard the Solar Dynamics Observatory satellite, a new
regime in precision astrometry has become possible. Tiny variations in the dynamic solar
shape at the level of a few microarcseconds have been measured and new ways of un-
derstanding the dynamical solar structure are being explored. This talk will introduce my
audience to the new field of precision solar astrometry.