Experts were surprised by how quickly artificial lighting made the night sky brighter. Over 50,000 stars were looked at by 'citizen scientists' between 2011 and 2022. They discovered that the night sky got 10% brighter every year.

In the January 20 issue of Science, researchers reported how an 18-year-old born in a place where 250 stars can be seen at dusk will only see 100 stars.

Light pollution is bad for more than just looking at the stars. Too much nighttime light can hurt people's health, drive migrating birds into buildings, disrupt food webs by luring pollinators to lights instead of plants, and stop fireflies from having babies (SN: 8/2/17; 8/12/15).

'In a way,' says Connie Walker, who is an astronomer in Tucson. 'Think about what this means for us. Not just stars. It's bad for us. It hurts animals that can't speak up.'

Walker works with the Globally at Night programme, which has brought together students from Arizona and Chile since the mid-2000s. Thousands of people from all over the world are now part of the campaign. Participants look at maps of stars that can be seen at different levels of light pollution and record their observational data on an app.

Christopher Kyba, a physicist at the Potsdam GFZ, says, 'I had my doubts about Globe at Night as a research tool.' From 2011 to 2022, Kyba and his team looked at 51,351 datasets.

'There is a lot of information, however, none of it is correct,' he says. 'Globe at Night is both a game and a way to learn about the world. More people make it better.'

Using these numbers and a 2016 global atlas of sky brightness, the group discovered that from 2011 to 2022, the night sky will get 9.6% brighter every year (SN: 6/10/16).

Satellites that measure global brightness missed the majority of that rise. Over the past ten years, these measurements showed that the light level went up by 2% each year.

Kyba gives more than one reason. Since 2010, LEDs have been used instead of high-pressure sodium lamps in many outdoor lights. LEDs are cheap and good for the environment.

LEDs give off more short-wavelength blue light than sodium bulbs, which scatter more air particles than orange light, making the sky look brighter. Since satellites can't see blue light, they don't know how much pollution LEDs cause.

Signs or window frames that shine toward the horizon may not be seen by satellites.

Dr John Barentine thought that satellites would underestimate the amount of light pollution. He was astonished by how much he had done wrong about the situation. 'This report shows that the amount of light pollution in the world is underreported.'

The good news is that it can be repaired without making big changes to technology. Scientists and governments need to get people who use lights in the evening to change.

Kyba says that the easiest way to fix light pollution is to just flip a switch. “Yes. It doesn't address the social problem, which is that billions of people's choices cause light pollution.

It's easy to make floodlights and parking lot lights flicker or turn them off at night.

Kyba said that a church in Slovenia changed from four 400-watt spotlights to one 58-watt LED under a cutout to light up the outside of the building. In 2018, Kyba cut its waste of energy and light by 96%. Even though the chapel was brightly lit, the grass, trees, and sky were all dark.

'If you could make that happen every day in our society, it would mean you could lower the amount of light in the sky by a lot and still have a bright environment and good vision while using a lot less energy,' he says. 'A dream.'

Consultant for dark skies Barentine thinks that the public will soon become aware and act. The fire on the Cuyahoga River in Cleveland in 1969 caused the environmental movement of the 1960s and 1970s, which led to the Clean Water Act.

He says that 'river-on-fire' light pollution will happen.