Fireball streaks across the sky over Pittsburgh

A comet-like object streaked quickly across the early morning sky of Pittsburgh on Wednesday, a burst of bluish-white light before disappearing into the darkness.

While there were reports of a giant meteor being visible on the East Coast, this particular object was actually something much smaller.

“A tiny piece of rock anywhere from the size of a grain of sand to a coin plummeted through our atmosphere and basically burned up over our heads, even kind of exploded a little bit,” said Charissa Sedor, an astronomy expert at the Carnegie Science Center’s Buhl Planetarium. “It was quite a show this morning.”

Duquesne University’s women’s rowing team was practicing on the Allegheny River before dawn when the explosion distracted 19-year-old sophomore rower Jillian Peters at around 6:25 a.m.

“We were in the middle of practice and there was a bright blue light,” said Peters. “It looked like a shooting star but it was much bigger and brighter. It looked huge. I thought it might be a comet or a meteor. It had a long, blue tail and it looked like it was on fire. We didn’t know what it was. Someone thought it was an airplane. I was like, ‘There are no rocket ships around here.’ ”

Peters said the team was near the David L. Lawrence Convention Center, and the sight of the object in the sky was enough to knock the rowers off their rhythm.

“I felt bad because I stopped for a bit and I was like, ‘Oh, we’re in the middle of practice, I can’t.’ And then after we stopped, I pulled up to the other boats and asked, ‘Did you guys see that?’ ”

But how could something as tiny as a grain of sand moving through Earth’s atmosphere cause an explosion that could be seen for miles?

“They are traveling very, very fast, like 50- or 60-thousand miles-an-hour up to maybe 150-thousand-miles-an-hour, which is what gives us this light show,” Sedor said.

Friction in the atmosphere causes the visual effect, said Sedor.

“We have this protective blanket that surrounds the Earth and we don’t really see it but things come from space, these tiny little objects that are constantly bombarding our atmosphere,” she said. “Once it hits the air and goes from the vacuum of space, where there is nothing to slow it down and hits our atmosphere, it starts to slow down very, very quickly, and that friction causes a lot of heat and it causes these things to actually burn up and vaporize in our atmosphere.”

Sedor said that while these objects can be mistaken for meteorites, which are objects that hit the Earth’s surface, they are actually called bolides — objects that end with a flash and have a lingering tail. Since the Earth is covered mostly by water, we usually don’t see them flashing through the sky but, every so often, when the sky is dark and it’s over a populated area, people can see them.

“This object likely didn’t make it down to the surface of the Earth. But it’s an awesome light show and all the more reason to keep looking up at the sky,” said Sedor.

Meanwhile, Peters said she has seen pictures and video of the bolide that burned up over Pittsburgh Wednesday morning, but it was much brighter in person.

“I probably won’t forget this,” she said.