Alteration of Twilight Sky Brightness Profile by Light Pollution 

Abstract

The phenomenon of twilight been stipulated as naturally dependent on the variables of solar depression, aerosol concentration and ozone composition. The unique color spectrum of twilight is attributed by ozone layer and aerosol, whereas its brightness is heavily relying on the altitude of sun below horizon. While all the natural dependent is being researched extensively, the impact of light pollution on the brightness of the twilight is not being explored thoroughly. The objective of this study is to find out the alteration of light pollution towards the natural behaviour of twilight sky brightness. Total of 84 data of twilight brightness was collected from 2014 until 2022 using Sky Quality Meter, and the specific location with profile classified as urban, suburban and pristine is investigated to study the impact of light pollution on twilight brightness. The result demonstrates that the stability of twilight brightness, which naturally factored by solar depression within the range of 18°, discovered to be heavy influenced by the zenith light pollution of the location sky, as evidenced by location that has zenith pollution of 17.11, 19.77, and 21.39, has horizontal twilight brightness of 14.84, 19.55 and 21.2 and solar depression during brightness stability at 11.5°, 15.67° and 17.49°.