Washington - Reports of a flash of light that streaked
across the sky over the US East Coast appeared to be a "single meteor event,"
the US space agency said late on Friday.
Residents from New York City to Washington and beyond lit up social media with surprise.
"Judging from the brightness, we're dealing with something as bright as the full moon," Bill Cooke of Nasa's Meteoroid Environmental Office said. "We basically have [had] a boulder enter the atmosphere over the northeast."
Cooke said the meteor was widely seen, with more than 350 reports on the website of the American Meteor Society alone.
'Super bright shooting star'
Robert Lunsford of the society told USA Today "it basically looked like a super bright shooting star."
The sky flash was spotted as far south as Florida and as far north as New England, the newspaper reported.
Matt Moore, a news editor with The Associated Press, said he was standing in line for a concert in Philadelphia around dusk when he saw "a brilliant flash moving across the sky at a very brisk pace... and utterly silent."
"It was clearly high up in the atmosphere," he said. "But from the way it appeared, it looked like a plane preparing to land at the airport."
Moore said the flash was visible to him for about two to three seconds, and then it was gone. He described it as having a "spherical shape and yellowish and you could tell it was burning, with the trail that it left behind."
Derrick Pitts, chief astronomer at Philadelphia's Franklin Institute, agreed that the sightings had all the hallmarks of a "fireball".
Pitts said this one got more attention because it happened on a Friday evening - and because Twitter has provided a way for people to share information on sightings.
He said what people likely saw was one meteor - or "space rock" - that may have been the size of a volleyball and fell fairly far down into the Earth's atmosphere. He likened it to a stone skipping across the water - getting "a nice long burn out of it."
Pitts said experts "can't be 100% certain of what it was, unless it actually fell to the ground and we could actually track the trajectory."
But he said the descriptions by so many people are "absolutely consistent" with those of a meteor.