Wasted light in this context is light that is not serving a purpose. For instance in my neighborhood there is a house that has security lights that shine well beyond their property lines and are triggered on sensor from across the street movement. These lights also illuminate upwards which provides no benefit. Simply controlling where light shines if you must have it is a good step to being a good neighbor and is better for nature as well.
Wasted light in this context is light that is not serving a purpose. For instance in my neighborhood there is a house that has security lights that shine well beyond their property lines and are triggered on sensor from across the street movement. These lights also illuminate upwards which provides no benefit. Simply controlling where light shines if you must have it is a good step to being a good neighbor and is better for nature as well.
unwanted light might be a better description
Oh I agree. Just was trying to provide how I interpreted the article.