Re ECF Project: 2009-10

Project Title: Hong Kong Night Sky Brightness Monitoring Network

Applicant: Dr. Chung-shing Jason PUN of The University of Hong Kong

Total Approved Grant: $499,970

Duration: 1/6/2010 to 31/8/2012

Project Status/Remarks: Completed

The objectives of the proposed program are: The project is a comprehensive year-long monitoring of the condition of light pollution in Hong Kong by studying the night sky brightness at ~15 urban and rural locations. Geographical variations and temporal characteristic of light pollution against both natural and artificial factors will be studied. Findings from the project would contribute to the overall environment of Hong Kong by promoting light pollution reduction and energy saving.

Summary of the Findings/Outcomes:
Measurement stations of The Hong Kong Night Sky Brightness Monitoring Network (NSN) had been set up throughout the city covering urban and rural settings to monitor continuously the variation of night sky brightness. Since May 2010, near 2.9 million night sky measurements were collected from 18 distinct locations. This huge dataset, the largest one on the sky brightness ever collected in the world, formed the backbone for studies of the temporal and geographical variations due to multiple natural and artiļ¬cial factors that are contributing to light pollution in Hong Kong.

Concrete evidence had been established on how human lighting affect the natural environment - the mean night sky brightness in the urban/suburban locations is much brighter than that of the rural locations. The effects of the switching-off of public and commercial lightings at both 11:00pm and 12:00am every night were also observed. It was also found that the lighting that could be turned off later in the evening contributed a significant fraction of the difference between in the sky brightness observed in urban versus rural. Findings from this project would not only support the importance of continuously monitoring of night sky in the future, but also strengthen the legislative need of outdoor lighting regulations.

Please refer to the Report of Hong Kong Night Sky Monitoring Network for details.