© University of Western Ontario
A composite photograph of the meteor that streaked across southern Ontario Sept. 25. It is believed meteorites landed in the Grimsby area.
Space rocks formed when the solar system was created billions of years ago are believed to have fallen to Earth near Grimsby in a fiery light show two weeks ago.

Astronomers will be digging through farmers' fields Thursday and Friday on the hunt for hunks of a meteor that blazed across the skies of southern Ontario Sept. 25 shortly after 9 p.m.

The beachball-sized meteor was first picked up by cameras operated by the University of Western Ontario's physics and astronomy department 100 kilometres above Guelph as the fireball streaked southeastward at a speed of about 75,000 km/h.

Astronomers at the university have traced the meteor's path and believe chunks of it may have landed above the escarpment within a 10-km radius of Grimsby.

"We're pretty certain something came down," said Phil McCausland, a postdoctoral fellow with the university's astronomy department.

"It's hard to put an X on the map and say, 'There,' because what happens is at the end of the fireball path the lights go out. There's no camera record of that."

It's likely small pieces of the meteor - anywhere between the size of a golf ball or a fist - made it through the atmosphere and hit the ground, he said.

"It could be dozens, it could be one or two. It's hard to say, but if it's one or two, they will be on the largish size - probably more than a kilogram."

Researchers are keen to find any of the meteorites because it's extremely rare to have their fall to Earth documented so well with photo evidence.

Based on all of the information already known about the rocks, it's possible for astronomers to determine which orbit they came from and learn more about the early history of the solar system.

"There's only a handful, perhaps a dozen, meteorites that have this kind of orbital information," McCausland said.

The rural area where the meteorites are believed to have landed is largely farmland with some forest.

McCausland has already spent several days over the past week searching for the rocks and interviewing landowners in the area.

He was expected to be back on the hunt again Thursday with other researchers.

"Even though the (cameras) we have narrows it down quite nicely, it's still a large area to search. We're still talking about 12 to 16 kilometres," he said.

Doug Welch, an astrophysicist at McMaster University, will be joining the search.

Welch monitors one of Western's meteor-seeking sky cameras at the Hamilton university.

The fireball that torched across the sky two weeks ago practically went directly overhead of the Hamilton camera.

"It's really spectacular. ... I've seen them live, but it's very rare for them to be this bright," he said.

Recovering meteorites that may have fallen gives researchers a rare opportunity to learn more about the formation of the solar system, he said.

"These are free samples from elsewhere in the solar system delivered to your door. We have sample-return missions that cost hundreds of millions of dollars."

Meteorologist and Grimsby resident Kerry-Ann Lecky Hepburn spends much of her spare time photographing the stars and planets.

But the night the fireball streaked towards Grimsby, she didn't have her camera trained on the sky. She was watching TV with her meteorologist husband in their home atop the escarpment.

"We saw a bright flash and thought, 'How can it be a thunderstorm. There shouldn't be any storms around.'"

A quick check online the following morning confirmed for Lecky Hepburn the bright light was a meteor.

"It would have been nice to see something other than just the bright flash," she said.

Researchers are calling for anyone who has found pieces of meteorite to contact them, as well as people in the area who witnessed the fireball.

Meteorites are typically dark, smooth on the surface, heavier than rocks of a similar size and able to attract magnets because of the metals they contain.

Under Canadian law, meteorites become the property of whoever owns the property where they are recovered.

Photos and video footage of the meteor can be found online.