China is putting the final touches on the world's largest telescope dish, measuring 500m across.
The Single-Aperture Spherical Radio Telescope (FAST), or Tianyan, covers an area the size of about 30 football fields.
Construction began in 2011, and it will be turned on in September after months of trials.
"The project has the potential to search for more strange objects to better understand the origin of the universe and boost the global hunt for extraterrestrial life," says Zheng Xiaonian, deputy head of the National Astronomical Observation at the Chinese Academy of Sciences.
The $250 million FAST dwarfs the Arecibo Observatory in Puerto Rico, which has a diameter of 300m.
It's not the world's biggest radio telescope - that honour still belongs to Russia's 1960s-era RATAN-600, which measures 600m across. But RATAN-600 is a circle of numerous rectangular reflecting panels, surrounding dozens of hectares of grass, while FAST is a massive dish made up of 4450 interlocking reflector panels.
Workers put in the final panel (Reuters)
China expects FAST to be the world's biggest and best telescope dish for two decades. It says the dish is for peaceful purposes.