About once every five to 10 years, a fireball streaks across the South Florida sky.
Appearing like a missile gone astray, it's actually a meteor big and fast enough to pierce the Earth's atmosphere. They rarely reach the ground, and astronomers say one has never caused damage in this region.
Still, hundreds bombard the Earth every day and, on average, one falls somewhere in Florida each year, said Eric Vandernoot, astronomy coordinator at Florida Atlantic University in Boca Raton.
"Tons of this stuff fall on Earth, but we're not aware of it most of the time," he said, which explains why night-sky watchers from Boca Raton to the Keys were astonished to see a burning meteor on Sunday.
Astronomers estimate its size as between a golf ball and a soccer ball and suspect it never touched down.
"It was probably too small to make it all the way through the atmosphere," said Susan Barnett, director of Buehler Planetarium and Observatory at the Broward College central campus in Davie.
Meteors aren't the only objects that fall from Florida's skies. Occasionally, aircraft parts also rain down and tend to make a bigger splash because that usually happens near an airport. Space junk also frequently falls back to Earth, but it has never been spotted over this state.
In the past week, meteors captured the spotlight.
The South Florida meteor appeared two days after a huge meteor, about 55 feet in diameter and weighing thousands of tons, crashed near Chelyabinsk, in western Russia, injuring about 1,200 people. Authorities said it was the largest outer space object to hit the Earth in more than a century.
"The shock wave, the result of the meteor's speed and mass, is what caused the damage," Barnett said.
That celestial calamity made South Florida residents more aware of the meteor here, even though the two events were totally unrelated, Barnett added.
"They were traveling in different directions, which means they came from different parts of space," she said.
When meteors approach the Earth, they can be traveling at more than 30,000 mph, so fast that they ionize the atmosphere and appear to be on fire. Such events, called "bolides," occur frequently around the globe but only once every five to 10 years over any given region, Barnett said.
"We're in a cosmic shooting gallery," she said. "But most of it burns up when it hits our atmosphere."
If a meteor hits the ground, it becomes a meteorite. Although that happens hundreds of times per year around the world, they usually fall into the seas or unpopulated areas and are rarely found. Because they contain iron, those that fall on Florida quickly rust from the salt air and humidity, Vandernoot said.
"There have been a total of five meteorites recovered in Florida in the last 600 years," he said.
Vandernoot said meteors shouldn't be confused with asteroids, which are large enough to be seen in outer space with telescopes and can also cause widespread devastation if they hit Earth. One theory is that an asteroid 6 miles in diameter slammed down near Chicxulub, Mexico, triggering the extinction of the dinosaurs about 65 million years ago.
Meteors aside, parts from aircraft usually fall as a result of mechanical problems.
In South Florida, the last major incident was in February, 2011, when a Delta Boeing 737 took off from Fort Lauderdale and metal pieces from its left engine spread over Port Everglades. No one was hurt and the plane, with 140 passengers on board, made an emergency landing.
A year earlier, in February 2010, a canoe-shaped part from an Atlas Air Boeing 747 cargo jet clanged into a Miami International Mall parking lot near a Dillard's department store. No one was hurt.
Space junk, or small pieces of human-made objects, falls to Earth about once a day. Larger intact spacecraft or launch vehicles re-enter the atmosphere about once a week, said Nicholas Johnson, NASA's chief scientist for orbital debris at Johnson Space Center in Houston.
"Most re-entries occur over the oceans or sparsely populated regions," Johnson said. "Typically, only one or two large objects are discovered around the world each year."
kkaye@tribune.com or 954-572-2085.
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