Monitoring Light Pollution to Save the Night Sky

April 15, 2015

Dr Jason Pun, Principal Lecturer in the Department of Physics

Hong Kong is famous for its brilliant night lights. The city's forever-changing skyline is lit up in a spectacle of multi-coloured lights that create a halo effect that in turn illuminates the urban sprawl and surrounding areas.

Thousands of commercial and residential properties across Hong Kong are illuminated by a vast array of traditional bulbs, neon lights, lasers, modern LEDs, increasingly powerful electronic billboards and ever-bigger video screens.

And many of these are left burning through the night to illuminate empty luxury shops, office towers, government buildings, car-free roads and people-less pavements.

Apart from the energy, health and environmental costs, this dazzling sight has another price – the loss of the night sky. In fact, Hong Kong has one of the worst light pollution problems in the world.

According to Dr Jason Pun, Principal Lecturer in the Department of Physics at The University of Hong Kong, the "night light" in Tsim Sha Tsui is over 1,000 times brighter than an evening night without light pollution.

For the last 10 years Dr Pun and his team have been researching the extent of light pollution across Hong Kong, educating the public its negative effects, and looking into ways that it can be reduced without the city losing its lustre as the "Pearl of the Orient".

"We can reduce the number of lighting fixtures in Hong Kong; we can reduce the amount of light used in each lighting fixture; we can reduce the number of hours of operations of this lighting; and finally proper shielding," Dr Pun said.

As part of his research Dr Pun set up a network of 18 night sky brightness measuring stations across the city, covering urban and rural areas, to monitor light pollution in real time. The data was fed back to HKU where it was automatically uploaded onto the project’s website. He has also been working with the Hong Kong Space Museum and other organizations to reach out to the general public and to school students, educating them of the negative consequences of light pollution.

Dr Pun is now planning to take the monitoring system overseas to record the night lights in locations around the world, with the ultimate goal of being able to reduce light pollution and reclaim the night sky for everybody.