CELPIP Reading Part 3: Reading for Information, with a free timed set

AOn a clear night in the 1950s, someone standing in a small Canadian town could usually see thousands of stars. Today most people see a few dozen at best. Astronomers estimate that the sky over most populated areas grows brighter by several percent a year, mainly because street and parking-lot lights send much of their glow sideways and upwards. The change is easy to miss, because it happens slowly and because people who grew up under bright skies rarely know what they are missing. A few towns have even begun to advertise their dark skies, and say visitors now come for a single night of stargazing.

BThe brightness is not only a loss for stargazers. Migrating birds, which use the stars to keep their course, can become confused by the glow of tall buildings and circle them until they are exhausted. Many insects are drawn to artificial light in a similar way, and moths that spend the night around a single lamp are not visiting flowers. Researchers have also linked bright bedroom light at night to poorer sleep in people, although they are careful to say that the evidence for wider health effects is still mixed.

CCanada was among the first countries to set aside areas where night lighting is strictly controlled. The first dark-sky preserve was created in Ontario in 1999, and there are now more than twenty across the country, from small provincial parks to Jasper National Park in Alberta. Inside them, outdoor lights must be shielded and kept to a warm colour, and park staff check them every spring. On a clear night in a preserve, visitors can still see the pale band of the Milky Way, which fewer than one in five Canadians can see from home.

DTowns outside the preserves can also make a difference, often without spending more. Many have replaced old street lamps with LED fixtures to save energy, and some now require any new outdoor light to point downward. The catch is colour: early LEDs gave off a cold, bluish light that scatters more in the air, so some towns that changed their lamps a decade ago found that their skies actually became brighter. Newer fixtures with warmer tones, and timers that dim lights after midnight, avoid most of that problem.