Photo from Xinhua shows a researcher is checking the file of solar eclipse on July 21.

Tibetan calendar with more than 2,000 years history has a unique Tibetan calculation way for the astronomical phenomenon. The book named as "Tibet astronomical almanac" authorized in September 2008 records solar eclipse phenomenon will appear in Tibet on 22 July (May 30 on Tibetan calendar).

Photo from Xinhua shows Kaduo, a Tibetan researcher is using a sand table calculator to calculate the astronomical phenomenon on July 21.