About Us


What is light pollution?

Light pollution is a form of environmental degradation caused by inappropriate and/or excessive use of artificial outdoor lighting that affects the natural environment. Poorly designed outdoor lighting not only wastes energy, money, and valuable earth resources, but also has negative impacts on our ecological systems and possibly our health. Saving electricity by reducing improper outdoor lighting also means less air pollution. This could in turn reduce global warming caused by the power generation process.


We are a group of researchers at the Department of Physics, The University of Hong Kong (HKU). 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.

Knowledge Exchange

We have also been active in spreading the message of dark sky to the public and informing members about the impact of light pollution and its current conditions. We have:

  • set up this dedicated light pollution website to communicate our research results and educational materials to the public. Since its launched in October 2011, the webpage is one of the leading websites on light pollution issues in Hong Kong and in the world;
  • organized roadshows such as the Light Pollution Science Roadshow at the Avenue of Star in Tsim Sha Tsui during Earth Hour 2013 and I Love the Night Sky - Star gazing is Fun in 2017;
  • organized competitions for the public and school groups in 2013-14, 2015-16 and 2018-19;
  • arranged lectures, workshops, and exhibition for secondary schools and various professional groups and stakeholders, locally and globally;
  • participated in multiple years of the HK SciFest organized by the Hong Kong Science Museum.
  • established an online public directory of good and poor lighting installments in Hong Kong: Lighting Directory. The interactive map displays both the locations and photographs of both good and poor lighting fixtures to provide to the public knowledge of the lighting deployed in their neighborhood. The Directory accepts submission via an online interface. The Directory also encourages people to report cases of improvements of any existing lighting, allowing us to record any reduction of light pollution in the community;
  • co-authored the Chinese version of the brochure titled Light Pollution. The brochure introduces the global light pollution condition, the impact of light pollution to astronomy and human health, and the importance of dark sky protection. HKU is responsible for translating the contents into Chinese and for enriching the brochure with local conditions on light pollution in Hong Kong, including the scientific studies of light pollution conducted by HKU both locally and globally.


Our knowledge exchange efforts have received accolades:

  • team member received the Secretary for Home Affairs' Commendation Scheme 2021;
  • team members were named co-recipients of the 2018 Dark Sky Defender Award by the International Dark-sky Association, the leading global organization in preserving the dark sky, awarded in “appreciation and recognition of their exceptional efforts to promote and advance the mission and programmes of IDA to preserve night skies by promoting quality outdoor nighttime lighting to reduce light pollution and its environmental impacts”;
  • Faculty Knowledge Exchange Award 2013 of the HKU’s Faculty of Science for the ‘Dimming the "Bright Pearl" - Informing the Public on Light Pollution’ project.

Community Engagement

We also serve as:

  • a member of the HKSAR government’s Working Group on External Lighting (since August 2018), an official body set up to “review the effectiveness of the Charter and to study how to further regulate external lighting” (Chief Executive’s 2018 Policy Address).
  • advisor to the Taiwan Hehuanshan area in its successful application in 2019 to be the first Certified International Dark-Sky Association International Dark Sky Park in Greater China.