Citizen Star Counts Show Night Sky Brightens 9.6% a Year, Outpacing 2.2% Satellite Trend
Updated
Updated · spacedaily.com · Aug 10
Citizen Star Counts Show Night Sky Brightens 9.6% a Year, Outpacing 2.2% Satellite Trend
1 articles · Updated · spacedaily.com · Aug 10
Summary
51,351 naked-eye reports from 2011 to 2022 found artificial skyglow rising 9.6% annually on average across 19,262 locations, a pace that could cut visible stars from 250 to fewer than 100 over 18 years.
Globe at Night volunteers matched constellations to star charts, capturing what people actually see from the ground after researchers filtered out twilight, moonlight and snow.
The ground-based trend far exceeds satellite estimates of 2.2% annual growth in lit area and 1.8% in radiance because VIIRS misses much blue LED light and poorly captures sideways emissions that drive skyglow.
Regional estimates varied—6.5% annual brightening in Europe and 10.4% in North America—and the sample was concentrated in those regions, so the result is not a full global measure.
The findings add to evidence that light pollution is already widespread: a 2016 atlas estimated more than 80% of humanity lives under polluted skies, though shielding, color choice and switching lights off can still curb the trend.
Why are human observers reporting night skies brightening far faster than satellites suggest—and what does that mean for the stars your child will see?
How far can city light erase rural darkness, and why are blue-rich LEDs making the Milky Way disappear faster than many measurements show?
If a child could lose sight of most stars before adulthood, which lighting fixes would actually preserve dark skies without making cities less safe?