Calgarians are being urged to see the light this week — and then consider turning it off.
Dark Sky Week is underway across the planet and astronomy professor Phil Langill intends to mark the occasion with an unusual challenge to local citizens.
He plans to ask Calgarians to turn off all non-essential outside lights one evening toward the end of the week, to see if there is a noticeable effect on light emanating from the city.
As well as teaching at the University of Calgary, Langill is director of Rothney Astrophysical Observatory near Priddis, and can therefore evaluate whether such a challenge can reduce the amount of city light leaking into the heavens.
He’s hoping thousands of Calgarians take the challenge, and is asking anyone interested to check the observatory Twitter feed @RAOastronomy for timing details.
“I have been measuring the darkness here at the observatory for many years. We have some very sensitive detectors that run 24/7 measuring whether or not the city of Calgary is making the sky brighter.”
“We are going to try to use social media this week to give Calgary the dark sky challenge — if we can get enough people to turn off their outside lights, maybe my detectors here at the observatory can actually measure that. Maybe if we can get a few thousand people to get aboard we can see if it makes a dent,” said Langill.
Light pollution is a growing issue across the world with its negative effects on human sleep cycles that raise the risk of physical and mental-health problems, such as depression, insomnia and weakened eyesight. Scientists have also long recognized that the ambient glare from cities causes serious issues for a host of animal species.
Yet, today’s lighting systems allow people to cut down on such pollution quite easily.
“We have so many great options in lighting. We can use light fixtures that shine directly down on the ground, where we need it, and we can also then use a motion sensor, so it’s only on when you need it — these very simple things, multiplied by thousands of people who live in cities, can make a big difference to the ambient light glow we live under all the time,” said Langill.
The sky is also being polluted by another form of man-made light — thousands of satellites are launched on average each month into lower Earth orbit for use in navigation, communication and security purposes. Within five years, hundreds of thousands of such satellites will be circulating above our heads, which is a concern to astronomers such as Langill who need to make precise study of the stars.
Though such commercial satellites are small, they still reflect the sun’s rays and their orbits are close to the Earth’s surface.
Langill recently used computer software to remove the light given off by passing satellites from an image of the skies over southern Alberta and was astounded at the difference.
“There were satellites everywhere. It was one of the most remarkable images I’ve ever seen. It just shows how many satellites are going through the sky at night,” he said.
Some companies involved in the satellite launch business are working to make them less reflective — among them, Elon Musk’s Starlink program plans to eventually place 40,000 such satellites in orbit. However, the sheer numbers involved will inevitably cause more light disruption to the heavens.
Langill said one problem is that most people have little idea what astronomers actually do, beyond taking nice photographs of space.
“People don’t realize we are so dependent on data and that we collect such data from actual photons from space. We have to wait to study that light, which has travelled across space, so we can then understand the physical conditions in that part of the universe creating this light.
“If there is light pollution from a city or a glint of light from a passing satellite that comes into the telescope, I could miss the opportunity from a little flicker of light from a distant galaxy that could lead to a fabulous discovery challenging our fundamental understanding of physics,” he said.