Study finds longest meteorite field
Print Edition
CHINESE scientists said yesterday that they have been examining three giant meteorites to find out if the world’s longest meteorite-strewn field is at Altay in the Xinjiang Uygur Autonomous Region.
Scientists at the Purple Mountain Observatory in Nanjing, capital of east China’s Jiangsu Province, said the meteorites were all from the same parent asteroid, as their chemical elements are identical.
The earliest dated discovery of the extraterrestrial stones was in 1898, when herdsmen in the Gobi Desert found a 28-ton silvery stone in the shape of a camel.
The Meteoritic Society later named it Armanty, and confirmed it to be the world’s fourth-largest meteorite.
Over 100 years later, a second one was found. Ulasitai weighed in at 430 kilograms.
It was not until 2011, when a third — the 5-ton Wuxilike — was found, that scientists began to notice the three meteorites were in a line, although across a distance of 425 kilometers.
“They are on the same axis from southeast to northwest, which piqued our interest,” said Xu Weibiao, meteorite curator with the observatory under the Chinese Academy of Sciences.
Xu said that all three were composed of the same chemical components and microelements. Several smaller meteorites have also been found in the field, all with the same chemical composition as the larger rocks.
“This suggests that the meteorites were all from the same parent asteroid before it separated as it entered the Earth’s atmosphere,” Xu said.
An ordinary meteor shower can scatter meteorites across dozens of kilometers.
Before the finding in Altay, the world’s largest meteorite strewn field was at Gibeon in Namibia, at 275 kilometers long.
Judging by the spread of the meteorites in the Altay field, its meteor shower is likely to have been the largest on the Earth.
However, there is no historical documentation about the incident and scientists speculate it might have happened in prehistoric times.
“A meteor shower of such a scale must have had a great impact on the Earth. If it happened after humans walked the earth, we often find cave painting depicting the incident in the area,” said Xu.
He said the team has used isotopic dating to determine when the meteor shower occurred.
An average of 20,000 meteorites fall to the Earth every year. Scientists use extraterrestrial stones to determine information about the universe and look for signs of life in space through chemical classification.
For example, scientists previously discovered evidence of magma activity on Mars some 200 million years ago after sampling a meteorite.
Next year, China’s Chang’e-5 lunar probe will collect samples from the moon.
“For the moon sample research, the observatory will use more advanced analytical equipment, which will greatly assist our petrological and mineralogical research,” Xu said.
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