China's oldest observatory is no longer suitable for nighttime use due to increasingly severe light pollution, scientists clarified on Tuesday.
Media coverage regarding the Zijinshan Observatory in east China's Jiangsu Province suggested that air pollution may be responsible for the observatory's inability to see the stars.
However, experts at the observatory said urban lighting has hampered observation.
The observatory is located in the eastern suburbs of Nanjing, capital of Jiangsu Province.
Zhang Yang, a staff member at the observatory, said the environment near the observatory has not met observation requirements since the 1980s.
"People look up at the sky but cannot even see the Milky Way or North Star, let alone conduct scientific observation," said Zhang
He added that other observatories set up in suburban areas, including the Shanghai Observatory and National Astronomical Observatories of China, face the same problem.
New observation sites for the Zijinshan Observatory were set up in 1999. Its sites can be found in northwest China's Qinghai Province, southwest China's Yunnan Province and Jiangsu Province.
"The parameters we lay down when selecting sites include the number of sunny days each year and meteorological visibility," said Zhang.
Experts worry that they will not be able to use the new sites for long.
"We started working at the Xuyi observation site in Jiangsu in 2006. After just five years, light pollution began to affect our observation," said Wang Sichao, a researcher at the observatory.
Wang said rapid urbanization in Xuyi County has created a brighter night sky that is unfavorable for astronomical observation.
"We may have to give up the site in less than 20 years," said Wang, who added that a qualified observatory site should have a useable observation period of more than 50 years.