For the entire history of life on Earth, dark nights followed sunlit days. In a little more than a century we’ve altered that natural pattern by illuminating our nights.

Excessive artificial light can harm humans and wildlife. Many species of plants, insects, birds and other animals benefit from the absence of disturbing artificial lighting. Ken Walczak will share the principles of responsible outdoor lighting and how you can make a difference.

Ken Walczak is the Senior Manager of Far Horizons at the Adler Planetarium in Chicago. He helped design and implement innovative instruments for light pollution research. He is a board member of DarkSky International and co-founded the local DarkSky Chicago chapter.