Light pollution
Unwanted artificial light that brightens the night sky and hides the stars and meteors.
Light pollution is light from streetlamps, buildings, signs and car parks that spills upwards and sideways instead of only lighting the ground. It makes the sky glow orange or grey above towns, so faint stars, the Milky Way and many meteors disappear. More than a third of the world's people now live under skies too bright to show the Milky Way.
It matters for more than stargazing. Too much light at night can confuse animals such as moths, bats, birds and baby turtles, and it wastes energy. The good news is that it can be fixed: shielded lights that point downwards, warmer and dimmer bulbs, and switching off lights that are not needed can all bring the stars back.
Some places protect their dark skies. Galloway Forest Park in Scotland became the UK's first Dark Sky Park in 2009, and many other parks and reserves around the world have followed. To see how light-polluted your own sky is, count how many stars you can see inside a constellation you know, then compare with a dark site on a holiday. For meteor showers, even moving from a town centre to the edge of a village can make a big difference.
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Level: Beginner Ages 7 and up