• A fleet of 500 drones lit up the New York City skyline with a Candy Crush advertisement on Thursday.
• While it didn't contribute significantly to light pollution in New York, astronomers say the event is a sign of our dwindling relationship with the night sky.

Five hundred drones launched into the skies above New York City Thursday evening, lighting up the Manhattan skyline with an advertisement celebrating the video game Candy Crush's 10-year anniversary.

In June, a similar performance in New York used hundreds of light-equipped drones to advertise the upcoming NBA draft.

"These sort of things should be stopped by laws if the reason is lacking, as it seems, before it is too late," Fabio Falchi, a researcher at the Light Pollution Science and Technology Institute who has studied light pollution for more than 25 years, told Insider. "Now, for the advantage of a corporation, the real stars will be replaced by these ultra-bright light of drones."

New York City is hardly known for its stargazing. Astronomers say one swarm of drones didn't add much light pollution to the already well-lit city.

"In the big scheme of things, it's of little consequence compared to the very many poor-quality outdoor lights that are on all night long in many US cities," John Barentine, an astronomer and consultant at Dark Sky Consulting, told Insider. "If it became a nightly event, or if there were many such displays happening at once, I would be more nervous about it."

Astronomers like Barentine say it's a sign of humanity's dwindling relationship with the night sky. "If I can't get people to care about stars they can't see anyway, then we'll only see more of this in the future rather than less of it. And that represents a real loss for people everywhere," he added.

Falchi pointed to companies in Russia, which are creating space billboards that will use satellites to display advertisements in low Earth orbit.

Goodbye darkness, my old friend

Light pollution, which can include brightening of the night sky from artificial light, can prevent us from getting a clear view of the stars.

Light pollution getting worse. A September 2021 study that used satellite data found that global light pollution increased by at least 49% from 1992 to 2017.

In a 2016 study, Falchi and other researchers estimated that even on the clearest night, the Milky Way was hidden to large swaths of humanity. In 2016, 99% of people in the US and Europe lived with some degree of light pollution each night, according to the study.

It might not be as deadly as other kinds of pollution, but light pollution can harm animals and people. Many studies have indicated that light pollution — from streetlights, light displays, and other sources — disorients migratory birds and plays a role in insect population decline. For humans, exposure to light at night can disrupt the body's biological clock, which is linked to health complications, including obesity, depression, and sleep disorders.