Pollution comes in many forms—including light. With a growing human population (the U.S. population has increased by 19.5 million since the 2010 Census)—comes more artificial light, a reality that is causing the night sky to brighten, making it harder for Earth’s creatures to see the stars.

According to a new study conducted by the Globe at Night project (operated by NOIRLab) and published in Science, visible stars have decreased significantly from 2011 to 2022 due to a 7 to 10% annual increase in sky brightness (aka skyglow).

“At this rate of change, a child born in a location where 250 stars were visible would be able to see only abound 100 by the time they turned 18,” said Christopher Kyba, researcher and lead author of the paper, in a statement from NOIRLab.

Light Pollution and Skyglow

As of 2016, more than 80% of the world (and 99% of U.S. and European populations) was overlooked by light-polluted skies. And with changing light technology comes a verified increase in skyglow (a romantic name for something that is anything but), resulting in a faux twilight of our own making, changing the way we see the sky after sunset and threatening our “right to starlight.”

Globe at Night used citizen scientists to collect its analysis (more than 50,000 observations in all), providing participants with a star map which they compared to the night sky at their given locations, the better to estimate naked eye limiting magnitude (NELM). This is a crucial dataset, as, according to the study, a rise in “background” radiance (skyglow) causes faraway or faint light points (stars) to disappear.

Not only is a lightened night sky less visually appealing, it also impacts human health (affecting our sleep cycles and leading to increased anxiety) and wildlife behavior, shifting migration patterns, hunting interactions, and more.

How Can We Protect the Night Sky?

The answer here is simple: use less light. Implementation, however, is a little more complicated. An influx of LED lights over the last decade has affected existing research on light pollution, leaving researchers unsure if the switch will ultimately help, or if the spectral changes are contributing to skyglow.

Plus, monitoring skyglow is hard. Satellites (our current option for direct measurement) cannot currently detect smaller wavelengths caused by the majority of LEDs and that make up most of the “ground radiance” visible to the human eye.

More research is needed, with subsequent policies implemented on national and international levels. In the meantime, keep your eyes on the sky, and switch off your lights—you may just save a star.