Calgary's skyline seen from the Rothney Astrophysical Observatory southwest of the city. (CBC)

Astronomers are hoping for a better view of the stars when Calgary residents switch off their lights Saturday night for Earth Hour.

Earth Hour is an international event with people all over the world turning out their lights from 8:30 p.m. to 9:30 p.m. to raise awareness about energy consumption.

"Earth Hour is not about light pollution per se, it's about how people impact their environment. But serendipitously, one of the best ways to save electricity is to flick off a light and so the sky's going to get darker," said Phil Langill, an astronomer at the Rothney Astrophysical Observatory southwest of Calgary.

The observatory plans to measure the change in the sky's brightness and is open to the public Saturday night, with a speaker talking about light pollution.

Langill is also hoping star gazers will record how many stars they can see at the observatory and in the city, using charts soon be added to the observatory's website.

"You don't need any special equipment, just with your eye you kind of see how many stars you can see and then you look on the charts and you try to match what you see in the sky to what's given in the chart," he said.

City of Calgary to turn off building lights

Despite lights going off at the zoo and some commercial buildings, power use in Calgary actually increased during Earth Hour last year.

Two factors are blamed for the jump in energy consumption during that period:

• The weather suddenly turned cold, forcing people to turn up the heat or furnaces to automatically kick in.
• The Calgary Flames and rival Edmonton Oilers were facing off in a significant game.

The Flames are scheduled to play the Minnesota Wild at the Pengrowth Saddledome on Saturday, but local Earth Hour organizers hope people will turn off their lights and appliances before turning on the game.

The City of Calgary will be turning off non-essential lights at all of its buildings, as well as street lamps on Saturday. City staff believe more Calgarians will sign onto the effort this year.

"Because of that awareness and as well, having a bit more prepared time to participate, we've had a chance to communicate to citizens and to our operations facilities managers to really make a stand for Earth Hour this year," said Sue Hayduk, environmental specialist for the city.