Scientists are asking residents to keep their eyes peeled for chunks of meteorite that may have crashed into the earth in southern Ontario.

Scientists at Western University in London, Ont. believe the meteorites hurtled to the earth last Tuesday night, when seven of the school’s all-sky cameras picked up a fireball shooting through the sky over St. Thomas, about 200 km west of Toronto.

The fireball was about the size of a basketball, the scientists estimate, and was first spotted over Port Dover, Ont. The fireball then “went dark” over St. Thomas.

“It spent about five seconds in luminous flight over southern Ontario,” Western’s Dr. Peter Brown told reporters Friday. “It was seen by a lot of people in the Toronto area, where it was clear.”

The recordings from the cameras showed that one or more rocks survived passage through the atmosphere, Brown said. Golf ball or baseball-sized chunks of meteorite likely hit the ground to the north and west of St. Thomas.

Scientists are asking residents to poke around their yards for fragments. Residents who heard a distinct whistling sound, like artillery, could very well find a chunk of meteorite nearby. They should look for matte black rocks, which will stand out against the regular rocks and stones in the area.

In Canada, meteorites belong to the owner of the land on which they are found.

“Meteorites, when they are freshly fallen and especially when the ground is still reasonably frozen like this, they sit on the surface and kind of look weird and attract your attention,” said Phil McCausland, assistant professor and meteorite curator at Western.

Meanwhile, the school will organize a search team to look through local fields.

Meteorites are important for scientists because they can reveal so much about the history of the solar system.

“The real value in this rock is the science side of it,” Brown said. “This is very unusual to have a fireball that produces a meteorite where you know the orbit. That’s only happened maybe 20 times in the past. So each one of those is like a Rosetta stone, telling us something about the solar system.”