Showing posts with label pre-dawn meteor. Show all posts
Showing posts with label pre-dawn meteor. Show all posts

Tuesday, May 11, 2010

Pre-Dawn Meteor Startles Drivers

The meteor seen Monday morning may have looked like this one.
Early-morning commuters in Maryland and as far away as Pittsburgh and Massachusetts were startled Monday by what was likely a spectacular meteor that crossed the sky in the pre-dawn darkness.

Dawn Teagle Dobbs spotted it as she drove south on Interstate 270 near Gaithersburg at 4:47 a.m. "At first I thought it was a shooting star, but it was huge and bright green with a tail," she wrote in a post to The Baltimore Sun's Weather Blog.

Ricky Diggler was motoring south on Route 100. "I saw a very large, greenish-yellow-colored object burning (with fiery tail) its way through the atmosphere in the east," he said in another blog comment. "It appeared to be heading for the Bay."

"Compared to the usual wisps of light very high up in the stratosphere that I usually see, this thing was huge," Diggler said.

Similar reports were posted to the blog from all across Central Maryland and the Eastern Shore, and as far off as Ashburn, Va., Pittsburgh, Greencastle and Gettysburg, Pa., and New Jersey and central Massachusetts.

The fireball sighting was at least the third such spectacle for Marylanders in less than a year.

On July 6, 2009, people in northern Baltimore County and nearby sections of Pennsylvania were rattled by the brilliant flash of a meteor and an accompanying sonic boom. The meteor's fiery entry into the atmosphere was captured on security camera tapes, but a subsequent search turned up no trace of the space rock itself.

Such was not the case on the evening of Jan. 18 this year, when another meteor dropped out of the twilight over Maryland and Virginia with a fiery flash and a lingering smoke trail that several people captured on their cameras.

Hundreds saw the fall, and a fist-sized chunk of that rock drilled through the roof of a doctor's office in Lorton, Va., narrowly missing its occupants before landing on the floor.

"Three [big meteors] in a year over a relatively populated area? That's pretty unusual," said Jim O'Leary, director of the Maryland Science Center's Davis Planetarium.

Although these objects encounter the Earth all the time, most fall over the ocean or other sparsely populated regions. "The chances of seeing it are pretty low," O'Leary said.

Most meteors are tiny bits of space dust no bigger than a grain of rice. They enter the Earth's atmosphere 40 to 60 miles up at such high speeds that the friction causes the air to glow and the meteor to vaporize, creating the visible light.

Fireballs are caused by much larger objects, said Denton Ebel, curator of meteorites at the American Museum of Natural History in New York City. "They could be all the way from a basketball to a small car," he said. When they arrive it's "like hitting a wall of air. The air can't get out of the way, so they break into pieces. They explode, essentially," becoming a cluster of objects.

Fireballs can vary in color. Heating during descent will ionize both the air around the meteor, and the rock itself, "sort of like a neon sign," Ebel said. Depending on what element of the air or in the meteor itself dominates, the colors can vary from yellow or red to blue or green.

Because of the fireballs' high speed and brightness, observers on the ground often underestimate their distance, O'Leary said. "Typically they're very high when you see them," he said. "But the impression is that sometimes, especially when they're every bright, that they're closer. In your mind, they're just beyond the trees."

From the descriptions provided by Weather Blog comments, the Monday morning meteor seems to have crossed Maryland and Virginia from roughly west to east, disappearing after a matter of seconds near the east or southeast horizon.

"Charlie" said he was driving on Route 23 in Forest Hill, Harford County, when he spotted the meteor as he neared Conowingo Road.

"I noticed this amazing bright streak of green light falling diagonally through the sky," he said. "I lost sight as it appeared to go behind the buildings at the intersection. I've never seen anything like it in my life."

From the Eastern Shore, a poster named "Jeff" said he was driving to work, eastbound in Salisbury, at that early hour. "I saw the green fireball," he said. "It appeared to have been traveling off the coast."

A poster named "Abbie," writing from much farther north, in central Massachusetts, said she watched as the meteor traveled from southwest to southeast, "right above the horizon. It was a very bright yellow fireball, with a train twice as long and just as bright, with pieces of fire breaking off."

"Mike" was in New Alexandria, Pa., near Pittsburgh, 167 miles northwest of Baltimore. He said, "I saw it very, very low above the southeast horizon … I am amazed at how bright it was for being so far away from me!"

For "Sam," who was driving south from Gettysburg on Maryland Route 97 about 4:45 a.m. Monday, the meteor appeared to be moving "across the sky, from west to east, at approximately 45 degrees above the horizon. Brilliant green in color, with trailing pieces. One of the most awesome things of that nature that I have ever seen."