Story highlights The streak, as bright as a full moon, was a meteor 1 yard in diameter, NASA says

It entered the atmosphere over Pennsylvania, heading toward the Atlantic

The FAA says it fielded calls about meteor sightings from Virginia to Maine

The night light show spurs a flurry of activity on social media

The streaking ball of fire Friday night above the East Coast did not, alas, signal the end to civilization as we know it.

Though you might get that sense from social media.

The sky lit up along the U.S. Eastern Seaboard with reports of "a thin streak of blue-greenish-white" from people like Chip Guy, who was driving in eastern Maryland when he and his family he spotted it.

"It didn't last more than eight or nine seconds, then it disappeared," said Guy, a spokesman for Sussex County, Delaware. "Frankly, I didn't think too much of it."

But his tune changed once he posted something about the presumed meteor on a local social media web page, which triggered a quick and hearty response.

That was just the tip of the online iceberg. Through Friday night, new reports of meteor sightings appeared every few seconds on Twitter, some of them from the metropolises of New York City and Washington.

"OMG I saw a real meteor in the Brooklyn's sky," wrote one person on Twitter, with the handle Curious Sergey . "It's all over the news now! I thought it is some kind of firework..."

The Federal Aviation Administration fielded calls about a meteor from Virginia to Maine, said agency spokeswoman Arlene Salac.

So what exactly was it?

Michael Kucharek, a spokesman for NORAD, said his agency heard about the sightings, too, and can confirm it was not from anything man-made, such as a plane or falling satellite.

On Saturday, Bill Cooke from NASA's Meteoroid Environment Office explained that the bright, fast-flying object was, in fact, a meteor.

The space agency's Jet Propulsion Laboratory defines a meteor as "light phenomena" from a meteoroid -- which is itself a comet or asteroid orbiting the sun -- that "enters the Earth's atmosphere and vaporizes."

It made for quite a show, producing a fireball as bright as a full moon and spurring more than 630 visual reports to be submitted to the American Meteor Society , as it soared southwest into the Atlantic Ocean.

But just because it was bright doesn't mean it was big. The meteor was one yard in diameter, about the size of an exercise ball, when it entered the atmosphere over eastern Pennsylvania, said Cooke.

That's still big enough potentially to produce meteorites -- which are meteoroids, or fragments thereof, that do manage to hit the Earth -- before burning completely. If it did, though, they fell harmlessly into the Atlantic, according to Cooke.

As anyone who has seen a shooting star can attest, it's hardly unprecedented for otherworldly objects to enter the Earth's atmosphere . And some of them do strike our planet, though they tend to be small when they do and strike unpopulated areas on land or plunge into the world's oceans.

There are exceptions, like the massive asteroid that many experts believe killed off dinosaurs. More recently, a meteor exploded over the steppes of southwestern Russia on February 15, a blast that scientists at Canada's University of Western Ontario estimated had the energy of about 30 early nuclear bombs

The related flash and boom shattered glass in buildings and left about 1,000 people hurt, authorities said.

There were no confirmed reports Friday night that the greenish streak spotted by so many actually impacted anywhere.

Even if it didn't, the mere possibility was enough to send chills down some stargazers' spines.