as the Pearl of Orient for its spectacular night scene, which is glittered with umpteen neon lights. Though manifesting the economic prosperity, the excessive illumination has aroused an implicit environmental problem: the light pollution. A recent survey by Chun Shing Jason Pun and Chu Wing So (2012) reveals that the average night-sky brightness of Hong Kong is 160 times brighter than a pristine sky, while in Tsim Sha Tsui this number staggeringly rises to about 1200, ranking the worst on the planet