Light pollution: finding a darker spot ten minutes away

Streetlights, signs and lit windows send light up into the air, which glows and hides faint stars. From a town you can still see the Moon, the bright planets and the brightest stars. For a meteor shower or the Milky Way, a park, field or quiet road ten minutes from the brightest lights makes a big difference, as long as a grown-up comes and it is safe.

What light pollution is

Light that goes up instead of down bounces off the air and the dust in it, and the whole sky glows a little. That glow is brighter than faint stars, so they disappear. From a big city you might count only a handful of stars on a clear night; from dark countryside, far more than anyone could count.

It also hides the Milky Way, the faint band of light made by the many stars of our own galaxy. Many children have never seen it.

What you can still see from town

Plenty. The Moon and every planet that can be seen with eyes are bright enough to show through town glow. So are the brightest stars and the main shapes: the Big Dipper, Orion's belt, Cassiopeia's W. Sky Tonight's card only names things that show from a town, so it works from an apartment balcony too.

Finding a darker spot

You don't need to drive for an hour. The biggest step is getting out from under the nearest streetlights and away from the brightest direction. A back yard with the porch light off, a school field, the far side of a park, or a quiet road on the edge of town can be far darker than the front sidewalk.

Look for open sky, especially low in the direction you want: south and east for most showers and winter evenings. Trees and buildings block the edges of the sky, and low down is where the town glow is worst anyway.

Turn off your own outside lights first.
Pick the darkest direction from your yard.
If you go somewhere else, choose a place you know by day, with a grown-up, away from roads and water.

Helping the sky

Families can help: point outside lights down, use warm-coloured bulbs, and switch lights off when nobody needs them. Groups such as DarkSky International campaign for the same, so that more children can see the Milky Way from home.

A simple test

Count the stars inside Orion's box (the four corner stars around the belt) on a winter night, or inside the Big Dipper's bowl in spring. From a bright town you may see none inside; from a darker spot, several. Try it from your front step and then from the darkest place you can reach, and you have measured your own light pollution.

More guides

“Read it, then go and look. The sky is the best page in the book.”