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You’ve probably seen those amazing videos of freshly hatched turtles making their way to the ocean for the first time. These turtles have an instinct to head towards the brightest horizon, but, due to an increase in artificial light at night (ALAN) in recent years, many baby turtles become disoriented and can end up dying due to dehydration or predators by moving towards the bright lights of a beach resort instead of the lights of the stars over the water.

The ��ݮ����Ƶ���� will be hosting an international conference this month addressing the issues around artificial light and light pollution.

“Artificial light at night is any light that isn’t natural,” explains , BSc'85, PhD'94, an associate professor in the in the Faculty of Science and a member of the local organizing committee for the (ALAN 2023). “If it’s not the moon, the stars or the sun, it’s artificial.”

Not all artificial light at night is bad, of course, as humans require light to safely navigate their surroundings. However, excess light poses issues for both humans and the natural world.

“It’s a complicated story,” says Langill. “How much light is the right amount needs to be researched carefully.”

How much light is enough

ALAN presents many challenges for the natural world, particularly for animals who don’t require light at night to navigate.

“Animals prefer the dark to hunt easier and to hide easier,” says Langill. “Once you introduce a light bulb outside, it changes animal behaviour and adds stress to their attempts to survive.”

Researchers featured at ALAN 2023 study the issues the natural world faces due to light pollution, as well as some potential solutions. The topics they are presenting on include governance and regulation, measurement and modelling, biology and ecology, social sciences and humanities, and health. The conference runs from Aug. 10-13.

The public will also have the opportunity to learn more about this topic, as there will be a  on-campus on Aug. 11 at 7:30 p.m. hosted by dark-sky expert , PhD, and featuring a panel of four of the ALAN researchers attending the conference.

The event will be a fun and educational exploration of light and light pollution. The audience will be able to answer a few questions, anonymously, using their smartphones. The event will conclude with a “sidewalk astronomy” opportunity as telescopes will be set up on-campus for free sky viewing, weather permitting.

For an astronomer like Langill, artificial light presents concerns about the ability to see the stars in the night sky. An analysis completed using data from the citizen science website , which asks people to measure and submit their night sky-brightness observations, found the sky has gotten brighter at a rate of about eight per cent per year over the past decade.

“This is a global problem,” says Langill. “If you extrapolate that rate out over a few generations and ask, ‘What will our great-grandchildren know about the stars?’”

While that may seem trivial, Langill says losing the ability to see the stars could have a negative impact on our mental health and our cultural myths and storytelling.

We can't lose sight of the stars

“When people don’t see the stars, they stop asking the big questions about life and the universe, and that’s something we all need to be able to do,” says Langill.

The good news is light pollution is a reversible problem. The main issue is changing people’s perceptions of the problem.

“Just because it’s easy to light your backyard, doesn’t mean you need to light your backyard with more light than is necessary and keep those lights on all night,” says Langill.

On a bigger scale, the people who build and light cities must revisit how they light their communities, as they currently operate on older lighting codes. And individuals will often not worry about their porch lights being on because there’s a streetlight that’s 100 times brighter 10 feet away.

“In the end, it’s about bringing awareness to the problem of light pollution,” says Langill. “This is effecting the natural world way more than we realize.”