Last month Fabio Falchi and his co-authors published some pretty astounding news about our night sky in the journal Science Advances.

By measuring artificial light pollution across the globe, they found that more than 1/3 of the people on this planet can not see the Milky Way, including almost 80% of North Americans.

Figure 3 from Falchi et al. 2016 indicating areas with light pollution. As you can see, not many dark (black) places are left.
Figure 3 from Falchi et al. 2016 indicating areas with light pollution. As you can see, not many places are left with no light pollution (black or dark grey areas).


I’m sure you’ve noticed a lack of stars when you look up at night. Light pollution can travel far and can even effect people who don’t live in big cities.

Light pollution can also be a problem for wildlife. The Audubon Society runs a program called “Lights Out” and they point out that because most birds migrate at night, some can be disoriented by lighting in buildings. This actually kills millions of birds as they fly into windows or circle brightly lit areas until they collapse.

There’s an easy solution to this – at least conceptually – and that is to turn off lights at night. The “Lights Out” program is specifically targeting lighting reductions during spring and fall migrations.

While it may not be feasible to attain complete darkness at night, new technologies like motion-activated or LED lights can be an improvement (as long as they aren’t in the blue spectrum). Tall buildings should have excess lighting turned out at night and streetlights can be hooded or turned downward.

Reducing lighting at night will help the birds and other wildlife that depends on dark nights, and could bring back the beautiful night sky for us as well. Can you imagine walking out your back door, standing in your backyard, looking up and seeing the Milky Way?

Check out the San Francisco Lights Out program (since light pollution travels and some of our local birds migrate through there) and consider talking with your local building managers about reducing excess lighting.

While we work on improving our night sky, you can use this map to find nearby areas with lower light pollution and better views of the stars as they were meant to be seen.

Where did the stars go?