By Roberta Attanasio In cities and towns all around the world, the nighttime glow of artificial light obscures views of the cosmos and contributes to an environmental problem called “light pollution.” Light pollution can also be present at smaller scale, for example in neighborhoods, or in homes. Often, this problem is caused by superfluous light. Solutions such as covering streetlights to direct beams downward or turning off unnecessary lights can be very effective. But why do we need to think about solutions? “For billions of years, biology evolved in a world where light and dark was controlled by the length of the day. When the sun went down, celestial sources…