Participating individuals are asked to go outside on specified dates at least an hour after sunset, then let their eyes adjust to the ambient light level, and observe a specific constellation: Orion or Leo in the Northern Hemisphere, Crux in the Southern Hemisphere.[1][2][12] The choice of a two-week span of dates near the new moon removes any effect on sky brightness from scattered moonlight, and observing well after sunset prevents any lingering light from twilight.[4] By comparing the stars they see with star charts showing stellar visibility under different light pollution conditions, they qualitatively measure light pollution.[14][15] Stellar visibility can also be measured for the project using a Sky Quality Meter, a tool used by amateur astronomers.[14] These light pollution data are then submitted to the coordinating website via a web browser.[16][17] The assembled data are provided to researchers and the public via a mapping interface that displays the data overlaid on Google Maps.[18]