Astronomers measure an elusive 'Rossiter-McLaughlin effect' during the last Venus Transit
A team of Italian astronomers performed a very difficult measurement for which it was necessary to use the most advanced instrumentation in combination with an unusual technique, so as to involve even the Moon as a natural astronomical mirror. The challenge was the observation of effect occurred during the transit of Venus across the Sun on June 6th, dubbed "Rossiter-McLaughlin effect". This is a phenomenon that occurs when a celestial body passes in front of a star, hiding a part of its rotating surface and that produces a temporary distortion in the profiles of the spectral lines of light coming from the eclipsed star. Astronomers led by Paolo Molaro, from INAF Astronomical Observatory of Trieste succeeded in this ambitious task, observing and measurirng the magnitude of this tiny effect. Their findings are published online today in a paper of the journal Monthly Notices of the Royal Astronomical Society.