GUIYANG, Sept. 25 (Xinhua) -- The world's largest radio telescope was put into use on Sunday in a mountainous region of southwest China's Guizhou Province.

Shortly after noon, in a karst valley in Pingtang County, hundreds of astronomers and astronomy enthusiasts witnessed the official launch of the Five-hundred-meter Aperture Spherical Telescope's (FAST) mission to explore space and hunt for extraterrestrial life.

Work on the nearly 1.2 billion-yuan (180 million U.S. dollars) project started in 2011, 17 years after it was proposed by Chinese astronomers.

The installation of the telescope's main structure -- a 4,450-panel reflector as large as 30 football pitches -- was finished in early July.