PINGTANG COUNTY, China — When hundreds of engineers and builders began clambering up a jagged hill in southwestern China to assemble a giant telescope in a deep, bowl-shaped basin, poor villagers sometimes crept over the sheer slopes to glimpse the country’s latest technological wonder.

“We’ve never seen anything like it, never imagined it,” said one villager, Huang Zhangrong, a sun-gnarled 66-year-old carpenter. “It’s a big circle, a big iron wok.”

The wok is the world’s largest single-dish radio telescope, and it officially began operating on Sunday, accompanied by jubilant national television coverage, after more than five years of construction. The Five-hundred-meter Aperture Spherical Telescope, FAST for short, is intended to project China’s scientific ambitions deep into the universe, bringing back dramatic discoveries and honors like Nobel Prizes.

Maybe even messages from aliens.

The telescope, which is in a majestic but impoverished part of Guizhou Province, embodies China’s plans to rise as a scientific power. The dish is made of 4,450 intricately positioned triangular panels and has a collecting area of 2.1 million square feet, equal to almost 450 basketball courts. At 1,640 feet in diameter, it will be roughly twice as sensitive as the world’s next-biggest single-dish radio telescope, the Arecibo Observatory in Puerto Rico, which is 1,000 feet across.