<human>:  What is light pollution and how can it be reduced?
<bot>: Light pollution is the introduction of artificial light, particularly outdoor light, which alters the natural environment and has a negative impact on the health and wellbeing of humans and other creatures. It occurs when too much light is cast into the night sky, reducing the visibility of stars and other natural sources of light. Ways to reduce light pollution include turning off outdoor lights after dark, installing shielding and motion sensors on outdoor lights, using LED lights, and using lighting design guidelines.