Light Pollution

Light pollution can drastically affect the number of stars visible in the night sky. Click on the picture to enlarge. Picture from

Step outside the average suburban home at night, and you’re likely to see the fluorescent glow of streetlights, soft yellow light streaming from the windows of homes, and security floodlighting. One thing you may not be able to see is the night sky. The light sources around us at night can scatter photons upwards into our atmosphere, creating light pollution that blocks our view of the stars – particularly those stars that are smaller, farther away from Earth, or dimmer. For many urban and suburban dwellers, the only Milky Way they’ll ever see comes in a brown candy wrapper.

Astronomers try to monitor levels of light pollution, because it has serious consequences for scientists’ ability to study our universe (Earth-bound telescopes, just like our eyes, are hampered by light pollution). Astronomers can’t be everywhere in the world, though, so to effectively keep tabs on levels of light pollution around the world, they need the help of ordinary citizens.

From October 9th through the 23rd, you can participate in the Great World Wide Star Count along with thousands of other amateur observers around the world. The idea is simple – everyone will observe the same constellation (if you’re in the Northern hemisphere, you will observe Cygnus) and count the number of stars that are visible. Then, observers will post their results online, where they can also view the project’s results. To participate, simply visit the Star Count website and download an activity guide.

If you are interested in learning more about the relationship between light and astronomy, look for the Science 360 show “Bring the Universe to Light,” coming back on the schedule at Morehead Planetarium and Science Center later this fall.

Casey Rawson is the Science Content Developer for Science 360.

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