Photo taken on Sept. 24, 2016 shows the 500-meter Aperture Spherical Telescope (FAST) in Pingtang County, southwest China's Guizhou Province. The FAST, world's largest radio telescope, measuring 500 meters in diameter, was completed and put into use on Sunday. (Xinhua/Ou Dongqu)

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.