China has built a new Schmidt telescope, the largest of its kind
in China, to keep track of near-earth objects (NEO) that could
threaten Planet Earth.
The telescope, measuring one meter in diameter, has been tested
in a branch observatory belonging to Mount Zijin Observatory under
the Chinese Academy of Sciences, in east China's Jiangsu Province.
Near-earth objects are comets and asteroids that have been
nudged by the gravitational attraction of nearby planets into
orbits that allow them to enter the earth's neighborhood.
Equipped with sensitive CCD (Charge-Coupled Device) detectors,
the telescope will help scientists document all NEOs, including
unknown ones, for further study, and enable scientists to know in
advance whether a NEO poses a threat to the earth, said Yang
Jiexing, a researcher with the observatory.
"It is quite likely that some asteroids and comets hit the earth
in the past, and it might happen again in the future," said
Yang.
"We built this detector to know in advance of any approaching
danger, and be able to figure out how to deal with it," he
said.
Scientists will take pictures of the NEOs and establish an
archive.
Uncertain evidence suggests that a meteoroid 45-90 meters in
diameter caused an aerial explosion that flattened about 2,000
square kilometers of pine forest near the Stony Tunguska River in
central Siberia in 1908, with the energy estimated to be equivalent
to that of about 15 megatons of TNT.
So far, more than 800 near-earth asteroids have been discovered
by scientists, including nearly 100 with a diameter over over 1,000
meters.
(China.org.cn, Xinhua News Agency November 22, 2006)
