BEIJING, July 20 -- Astronomers by the dozen are descending on southeast China in anticipation of this week's total solar eclipse, among them, one of the world's best-known eclipse experts.

    Jay Pasachoff is a member of the International Astronomical Union and a professor at Williams College in the United States. He arrived in Zhejiang Province Sunday to hold a lecture for eclipse-watchers.

    Using vivid pictures and simple words to explain the science behind an eclipse, Pasachoff impressed amateur and professional stargazers alike. Cai Tingni is a member of Hangzhou High School's Astronomy Club.

    Soundbite: Cai Tingni, member of the Astronomy Club of Hangzhou High School "The lecture is very helpful. It's a rare chance for Pasachoff, the astronomer of IAU coming to Hangzhou. We can listen to his illustration of eclipse principles with his over 20 observing experiences. That is really beneficial for us."

    Having devoted 50 years of study to the subject, Pasachoff has witnessed 26 total solar eclipses, 11 annular solar eclipses and 9 partial solar eclipses. He chose Anji in east China's Zhejiang Province as his personal observation spot for this year's event all the way back in 2007.

    Wednesday's solar eclipse will be one of the longest in recorded history.

    Xinhua News Agency correspondents reporting from Hangzhou.