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The Dark Side of Light

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Tsim Sha Tsui’s night sky is more than a thousand times brighter than a normal dark sky – making our light pollution probably the worst on the planet. Dr Jason Pun thinks it’s time Hong Kong saw the light.

Paris may delight in being known as the ‘City of Lights’, but a less romantic yet more apt name for Hong Kong might be the ‘City of Too Many Lights’. According to the results of data collected by HKU’s Night Sky Brightness Monitoring Network, at night our inner city appears to have the worst light pollution on the planet – more than a thousand times brighter than the natural dark sky.

The highest figures, at more than 1,200 times brighter than a night sky without light pollution, were recorded on the Tsim Sha Tsui waterfront, and even in rural areas such as the Wetland Park in Tin Shui Wai levels are 130 times the standard, most likely due to light coming from the nearby housing estates, streetlamps and public lighting.

Dr Jason Pun Chun-shing of the Department of Physics conducted the research, which was widely reported in the local press. His findings have prompted him to ask why, at a time when the global trend is to take steps to conserve energy and reduce pollution, is Hong Kong still lit up so excessively.

“A decade ago when I started the study many people were saying we’re the Pearl of the Orient and we should be bright,” says Dr Pun. “But, is this the only way to show that we are a prosperous city?”

Asked to comment on the Symphony of Lights, which nightly shines across the harbour as a tourist attraction, Dr Pun says: “From our data there is no strong evidence that it causes prolonged light pollution – but it certainly sends a particular kind of message to the public and to tourists.”

But it is not the inner city that is Dr Pun’s main concern: “Why are our outer urban areas so brightly lit? As far as we can tell, our city’s suburbs are as bright as or even brighter than other city centres.” He then clarifies that research elsewhere is not as comprehensive as his in Hong Kong. “It’s a relatively new field, we’re first to do this kind of systematic study on this scale. But I have seen initial findings of other studies and as far as I recall I did not see anywhere as bad as Hong Kong.”

"Brightness levels reduced by two-thirds when the lights went off, and suddenly you could see stars. It was a dramatic demonstration of what we’re missing."

Dr Jason Pun Chun-shing

The Department did a Science Roadshow on the harbourfront in Tsim Sha Tsui on the day Earth Hour was held.
Mr So Chu-wing (left), Project Manager of Hong Kong Night Sky Brightness Monitoring Network and also a PhD student in the Physics Department, and Dr Jason Pun (right).

Left: The Department did a Science Roadshow on the harbourfront in Tsim Sha Tsui on the day Earth Hour was held.
Right: Mr So Chu-wing (left), Project Manager of Hong Kong Night Sky Brightness Monitoring Network and also a PhD student in the Physics Department, and Dr Jason Pun (right).

The full version of this article was originally published in Bulletin. Please click here to view this HKU publication.

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