Fireball Flashes Above Ontario and Parts of the U.S.

A fireball that soared over Ontario, Canada, early on Saturday was the sixth object to be detected in space before it struck Earth, the European Space Agency said.

In the early hours of Saturday, word spread in the community of professional and amateur astronomers that a meteor was on its way and that observers should keep their telescopes and cameras trained toward the sky.

The Minor Planet Center, which tracks objects in the solar system, said the meteor entered Earth’s atmosphere at approximately 3:27 a.m. Eastern Standard Time, over Brantford, Ontario.

The fast-moving object, which has the temporary designation of #C8FF042, was detected in images taken at Mount Lemmon Survey near Tucson, Ariz., the Minor Planet Center said.

Mike Hankey, the operations manager for the American Meteor Society, was in Maine, where he was setting up cameras to monitor the sky, when he got a call about the meteor around 4 a.m. from someone in Germany.

He said messages about the meteor had started circulating about three hours earlier.

“When these things happen, the astronomy community wants to know where the impact took place and, if meteorites survived, they want to recover them as soon as possible,” Mr. Hankey said.

A fireball is a meteor generally brighter than the planet Venus in the morning or evening sky, according to the American Meteor Society, which had received 33 reports of a fireball from people in Maryland, New York, Ohio, Pennsylvania and Ontario as of Saturday afternoon.

Some people in and near Hamilton, Ontario, said on social media that they had heard a loud boom. Astronomers were able to use these reports, as well as radar readings, to determine where the meteorites were likely to have hit Earth.

“There is a chance if there are meteorites that survived that they might be recoverable near Grimsby, Ontario, or St. Catharines, Ontario, near the Niagara Falls area,” Mr. Hankey said.

An estimated 40 to 100 tons of space material strike Earth every day, and most of it is very small particles, according to the European Space Agency.

Mr. Hankey said astronomers did not know the size of the meteor on Saturday. A meteor is what a meteoroid, a small piece of asteroid or a comet, becomes when it enters Earth’s atmosphere. A meteoroid that survives its fiery descent and hits the ground is called a meteorite.

Global efforts to identify large asteroids, which can span kilometers in diameter, and to detect them before impact have grown in recent years, according to the European Space Agency.

Since 2008, five other objects have been detected in space before they struck Earth, the result of improved observation technologies and greater global collaboration, the agency said.

The ability to detect these space objects before they hit Earth gives the authorities the opportunity to warn people to stay away from windows if a medium-sized meteor is expected to fly by and explode, which could break windows, or to use asteroid deflection missions to prevent larger ones from striking.