The mainland has launched a research rocket to gather high-altitude scientific data, with the experiment attracting widespread public attention because it was visible in the evening sky across many provinces.
Scientists conducted the test on Monday for research purposes, the Chinese Academy of Sciences' National Space Science Centre said yesterday in a statement posted on its website. It was issued following heated online speculation that it was a military experiment.
The experiment, which may have lasted less than 10 minutes, started around 9pm with the launch of a sounding rocket, carrying scientific instruments, at the Xichang Satellite Launch Centre in Sichuan .
The flight was designed to collect raw scientific data from different layers of the atmosphere, with scientists most interested in the ionosphere, the earth's magnetic field, cosmic rays, the sun's ultraviolet and X-rays and meteorite dust.
"The experiment has reached expected objectives by allowing scientists to obtain first-hand data regarding the space environment at different altitudes," the centre said in Xinhua.
The rocket carried equipment such as a Langmuir probe to study plasma, a detector for high energy particles and a magnetometer.
At the end of its climb, the rocket released barium sulphate, forming a large cloud of ionised particles visible to the naked eye.
Internet users in cities including Chongqing , Kunming , Chengdu , Wuhan , Changsha , Zhaoqing and Haikou reported seeing an unusually large and bright object in the sky at about 9pm, reports run by major news portals including Sina and People.com.cn  said.
The reports said some internet users had speculated that the experiment had been conducted by the People's Liberation Army and was another attempt to shoot down a satellite.
Liu Yu, an astronomer at the academy's Yunnan Astronomical Observatory in Kunming, said the atmosphere protected human and other life forms by blocking harmful cosmic radiation such as ultraviolet rays, but it also blinded many scientific instruments.
By sending instruments to high altitudes, scientists can see things that are invisible from the ground and perform studies such as using the sun's corona to forecast solar storms.
China conducted a similar experiment last month in Danzhou , Hainan , the academy said. The data gathered in that experiment would be used to improve the safety of power grids and spacecraft, it said.