Travel agencies, hotels, airlines and even online vendors are cashing in on the longest solar eclipse of the 21st century, which will pass across China next Wednesday.

The July 22 eclipse, which will last up to six minutes, the longest until the year 2132, has become the promotional tag line for the tourism industry in cities along the Yangtze River, including Shanghai, Suzhou and Wuhan.

"It is a perfect pitch for us. All 50 star hotels in downtown Suzhou have prepared free special glasses for astronomy lovers. The hotel room occupancy rate will definitely go up," said Wu Min with the marketing department of Suzhou Tourism Bureau.