Light is different in the vertical environment of the city. We chose to live on a numbered street so the house runs east-to-west and has a south facing light shaft. This brings light down through the house especially in the summer. Even with that, sunrise and sunset are wonderful at the highest levels but the lowest levels might not even know those events happened till an hour or so later. We are a little sun deprived but are working on solutions that include more opportunity for sun, gardening space, views and breeze.
That doesn’t mean we are light deprived. On the contrary, light in the city is pervasive – the sun provides natural light during the day while street lights, headlights, bike lights, front stoop lights, shop 
lights, billboard lights, and emergency lights (to name a few) shed continuous light through the night. There are lots of good things about this night light – safety, beauty, and the ability to navigate. But there is a lot bad too. People need darkness to set their circadian rhythm properly; to stay healthy, and they need access to the night sky for a sense of awe and wonder.
The International Dark-Sky Association works to protect and preserve the night sky from the careless use of artificial light. The IDA is working with United Nations as it commemorates the achievements of light science, its applications, and its contributions to humankind during 2015, the International Year of Light.
The alley behind our house is lit with three street lights. This alley is well traveled day and night so light is key to safety and security. The problem with the streetlight directly behind us was that the light was shinning so brightly inside the house…and not just our house but into the homes of our four neighbors to the south and three neighbors across the alley. So brightly inside that there was no need
to turn on the lights. The light in the yard and on our deck made it impossible to enjoy the night sky let alone see a star.
Enter the Philadelphia Streets Department; our dark sky heroes. We requested that the light be modified with a cowling to shield the light away from the houses and yards and direct it into the alley. As a first step toward full shielding, the Streets Department changed the lens on the streetlight from a rounded full head to a flat lens. The difference is dramatic. The alley is brighter and our deck is dark. We have to turn on the lights in our den to be able to see at night and the light pattern on our neighbors is lower and less intense.
I want to thank all of the people at the Streets Department for their thoughtful and expedient work – from customer service to engineering to the traffic department – we are very happy with our new found dark sky. Be warned, our neighbors would like to continue the effort to fully shield that streetlight so you may not have heard the last from us. For now though thank you very much we are finally able to see the stars.
