CALGARY, Alberta (Reuters) – A massive ball of fire that lit up the skies over two Western Canadian provinces on Thursday evening was likely among the biggest meteor events to be witnessed in Canada this year, one expert said.

The fireball, which streaked through the darkening skies over Alberta and Saskatchewan at about 5:30 p.m. Calgary time, likely weighed between one and 10 tons and shone brightly enough to be seen over an area 700 km (435 miles) wide.

"It was somewhere between the size of a chair to the size of a desk," said Alan Hildebrand, a planetary scientist at the University of Calgary and a coordinator of a fireball reporting service.

"This one was pretty spectacular. For this year it will be one of the biggest that happens over Canada.... Something like this radiates like a billion-watt bulb. It's pretty bright light in the sky."

Hildebrand said the meteor may have broken into hundreds of smaller meteorites that likely landed in central Saskatchewan near that province's border with Alberta.

The fireball lit up the skies for about five seconds, he said.