Research

We have been working on measuring the night sky brightness and studying the impacts of light pollution to the environment since 2003. With the support from HKSAR government’s Environment and Conservation Fund (ECF) grants and HKU’s Knowledge Exchange Impact Project grants, we have been:

  • used traditional astronomical techniques (telescope and camera) to conduct the first research of light pollution problem in Hong Kong taken under rigorous scientific standard in 2003. For details, please refer to this thesis;
  • initiated the a citizen science project A Survey of Light Pollution in Hong Kong in 2007. At the end of this 18-month survey with over 170 participants coming from different walks of life contributing 2,000 individual readings of the night sky conditions, the first Hong Kong light pollution map – taken over 199 distinct locations – was created. For details, please refer to the press release, the project report, a peer review article and this thesis;
  • developed the Hong Kong Night Sky Brightness Monitoring Network (NSN) in 2009 – an automatic night sky measuring stations were established at 18 sites around Hong Kong to continuously monitor the quality of the night sky. Over five million data entries were collected, making it the largest long-term single database then on night sky brightness ever collected in the world. Results from this two-year study clearly revealed that artificial exterior lighting is the main source of light pollution in Hong Kong. For details, please refer to the press release, the project report, a peer review article and this thesis;
  • launched the Globe at Night – Sky Brightness Monitoring Network (GaN-MN) project to conduct an international long-term monitoring of the night sky. The project aims to promote a standardized night sky measurement method for worldwide research on light pollution, to promote public engagement through live light pollution data and night sky measuring programs, and to highlight the negative environmental impacts of abusive artificial lighting for the general public and policy makers. For details, please refer to the project website.

By analyzing the data recorded at different times, locations, and meteorological conditions, we are currently investigating the following questions:

  • What is the overall light pollution condition in Hong Kong?
  • How does the night sky brightness vary with location, locally and globally?
  • How does the night sky brightness change with time?
  • How much does artificial lighting affect the night sky?
  • What is relation between cloud coverage and the night sky brightness?
  • What is relation between moonlight and the night sky brightness? etc

We analyse different kinds of data, include but not limited to:

  • Photometric data acquired through CCD photometry
  • Sky brightness data measured by semi-conductor devices such as SQMs and TESS Photometers
  • Spectroscopic data
  • All-sky imagery
  • Panoramic imagery
  • Remote sensing data acquired by the International Space Station and night lights observing satellites
  • Meteorological data
  • Air quality data
  • Geospatial data such as population and land use, etc.