Hundreds of people in northwest China's Gansu Province saw a UFO on the night of December 11. Witnesses said that a strange shining object swept through the sky at 11:36 PM, followed by a loud blast that resembled bombs dropping. People within a 100-square-kilometer area around Lanzhou, the capital of Gansu, reported feeling the earth tremble.
A driver surnamed Zhang said that he was driving from Lanzhou to neighboring Yongdeng County when he saw a fireball with a three-meter-long trail flying from west to east. Immediately after, he heard two noises resembling thunder.
The local public security department said that it received more than 700 reports of the event.
Two experts from the provincial Seismology Bureau said that the shockwave was not seismic activity from an earthquake. They believe that it was the result of a meteor impact about 60 kilometers from Lanzhou. The shockwave caused by the falling meteorite was equal to a blast from 30 tons of dynamite.
Liu Chengchang, a specialist in the effects of astronomical events on geology, attributes the meteorite fall to the Geminid meteor shower. While the light show it provided was expected to peak during the early morning hours of December 14, activity began around the 9th and is tapering off through the 16th.
Other UFO sightings were reported from the eastern urban region of Lanzhou on November 23 and from Gulang County, Wuwei City, on December 3. The periods of time between sightings, when considered together with the earth's orbit, gravity and other factors, make it extremely likely that the December 11 fireball was a meteorite, according to Liu.
For a meteorite to reach the Earth, its parent meteoroid must have come from an asteroid, which is composed of sufficiently sturdy material for the trip through the atmosphere. Meteoroids of asteroid origin make up only about 5 percent of the total meteoroid population, which is primarily cometary.
A farmer surnamed Jia was on his way to home when he saw a fireball crash into his rice paddy. The next day, his wife found a strange stone weighing 2.15 kilograms in the field. She believed that it might be the falling meteorite, but there was no evidence of impact in the area where the stone was found.
Experts said that a 2.15 kilogram meteorite would definitely create a large crater when it struck the ground. Although Jia's stone is similar to a meteorite, further testing must be conducted to be certain.
Although other suspected strike locations have been reported, experts have so far ruled them out and the December 11 meteorite has not yet been found.
Astronomers estimate that each square kilometer of the Earth's surface collects an average of one meteorite fall once every 50,000 years.
(China.org.cn; Lanzhou Morning Post, translated by Wang Qian, December 15, 2004)
