MAY 01, 1980
Last year when John Eddy and Aram Boornazian reported evidence that the Sun has been contracting about 2 arc seconds per century, the announcement was greeted with excitement tempered by skepticism. Their evidence, reported at the American Astronomical Society meeting last June (PHYSICS TODAY, September 1979, page 17) and still not published, was obtained by analyzing measurements of the Sun’s transit made at the Royal Greenwich Observatory (from 1836 to 1953) and the Naval Observatory (from 1864 to 1953). Now Irwin Shapiro of MIT has published an old analysis of 23 transits of the planet Mercury in front of the Sun in the period 1736–1973. He finds that the solar diameter cannot be decreasing more than 0.3 arc seconds per century, with a 90% confidence limit.
© 1980. American Institute of Physics
