The world's newest and biggest radio telescope has started its hunt for E.T.
The Five-hundred-metre Aperture Spherical Telescope (FAST) covers an area the size of 40 football pitches in Guizhou Province, southwest China.
The $250 million telescope sits in a valley, surrounded by hills. It took five years to build, and forced 10,000 people living there to move.
With a diameter of 500m, FAST dwarfs the second-biggest telescope in the world - Puerto Rico's Arecibo Observatory, which is 305m across.
"Bigger is better in radio astronomy. The signals in radio astronomy are so weak that you need big telescopes to see it," says University of Manchester radio astronomer Peter Wilkinson.
FAST, from the side (Getty)
FAST is too big to move, but each of 4450 triangular panels can be individually adjusted to point at different parts of the sky.
"When we follow a star, the reflector must compensate for the rotation of the earth, so that it always points to the star," says Wang Qiming, chief engineer of FAST's electro-mechanical system.
"Through our technology, the reflector will be able to observe the stars for an extended period of time."
FAST's immense size and accuracy will boost efforts to detect signs of alien life by "five to 10 times", according to the National Astronomical Observatories at the Chinese Academy of Sciences.
"When everyone is focusing their attention on how grand the structure is, what's most impressive about FAST is its precision," says said Zhu Lichun, chief engineer of FAST's measurement and control system.
It'll also look for pulsars, gravitational waves and radio emissions.
The Russian RATAN-600 telescope is wider, but consists of a ring of panels rather than a single dish.