During 2007 to 2009, we conducted "A Survey of Light Pollution in Hong Kong" and concluded from 2,000 data sets that Hong Kong night sky in the worst polluted urban areas is at least 500 times brighter than some unpolluted rural areas. Moreover, we found that the late night skies (at 11:30pm) are generally darker than earlier (at 9:30pm), attributed to turned-off public and commercial lightings late at night.