Tonight at 8:30pm local time the world celebrates Earth Hour – a chance to turn off lights and enjoy the night sky. It’s also a reminder that we can fight light pollution every night.

According to the International Dark-Sky Association, 30 percent of all outdoor lighting in the U.S. is wasted. That adds up to $3.3 billion and the release of 21 million tons of carbon dioxide per year. This squandering of resources is not only detrimental to our changing climate but light pollution also impacts human health and wildlife.

To do your part:

– switch off unnecessary indoor lighting at night, including your office building.

– use motion detectors and timers

– purchase “Dark-Sky Approved” outdoor lighting that is fully shielded and directed down

– keep your blinds drawn at night to keep light inside

For more inspiration, visit this interactive map of night-lights courtesy of NASA’s Earth Observatory.