The world's largest radio telescope has begun searching for signals from stars and galaxies and, perhaps, extraterrestrial life in a project demonstrating China's rising ambitions in space and its pursuit of international scientific prestige.
Beijing has poured billions into such ambitious scientific projects as well as its military-backed space program, including its second space station earlier this month.
Measuring 500 metres in diameter, the radio telescope is nestled within a stunning landscape of lush green karst formations in southern Guizhou province.
It took five years and $US180 million ($A236 million) to complete and surpasses that of the 300-metre Arecibo Observatory in Puerto Rico, a dish used in research on stars that led to a Nobel Prize.
The official Xinhua News Agency said hundreds of astronomers and enthusiasts watched the launch of the Five-hundred-metre Aperture Spherical Telescope, or FAST.
Researchers quoted by state media said FAST would search for gravitational waves, detect radio emissions from stars and galaxies and listen for signs of intelligent extraterrestrial life.
"The ultimate goal of FAST is to discover the laws of the development of the universe,'' Qian Lei, an associate researcher with the National Astronomical Observatories of the Chinese Academy of Sciences, told state broadcaster CCTV.
"In theory, if there is civilisation in outer space, the radio signal it sends will be similar to the signal we can receive when a pulsar (spinning neutron star) is approaching us,'' Qian said.
Earlier this month, China launched the Tiangong 2, its second space station and the latest step in its military-backed program that intends to send a mission to Mars in the coming years.
In August, the country launched the first quantum satellite experts said would advance efforts to develop the ability to send communications that can't be penetrated by hackers.