Below are the first reports we have received. If you heard or saw something similar, around the same time, please leave a comment. Include the time, your location, which direction you saw the object or flash, a description of what you saw, and note any boom or other sound you heard, as well as the time lapse between flash and boom.
The York Dispatch: In York County, Pa., police officers from Penn Township, Southwestern Regional and Newberry Township reported seeing a flash and hearing a boom around 1:15 a.m. Monday, July 6, according to local 911 centers. Officials in Harford County, Md. also reported seeing a flash and hearing a boom near the Mason-Dixon Line.
Capital Gazette: An Annapolis city police officer reported that she and her partner both saw what she described as a "bright blue light in the sky" just after midnight. It was followed by "a light with a tail, falling from the sky," according to our informant. Annapolis police reported hearing a similar report on Baltimore County police radio.
Gary Moon, reporting to The Sun's News Tips: "I heard and felt a deep earth blast similar to an earthquake, which shook my home in Glen Rock, Pa., early Monday morning. I thought I would hear MUCH more about this one ... nothing."
Deborah Markow, Havre de Grace: "Last night, couldn't sleep, went out on back deck, laid on lounge, eyes closed and then it was like someone pointed a flash light in my eyes it was so bright. I saw another one streak through the sky ... It was one of the most thrilling sights to behold a ball of fire flying through the sky."
I have not yet seen any meteor reports of this event on the American Meteor Society's Fireball Sightings Log, but it's early yet, and this fireball, coming in the wee hours after a long holiday, probably did not catch many people out and about.
Which makes reports like these, and yours, all the more important. If you saw this object, be sure to leave a report with the AMS, too.
But judging from the descriptions, it almost certainly was a fireball, which is simply an especially bright meteor, vaporizing with an impressive flash.
Here's a pretty good example on video.
They are sometimes followed by a sonic boom, which would explain the booming noises in the reports. Some fireball observers - though none yet for this event - also report a crackling or hissing sound that is concurrent with the meteor's flash and which has never been fully explained scientifically.
Although meteor rates begin to pick up in July, this is not the peak time for any particular meteor shower. It seems likely this was a "sporadic," or isolated meteor that just happened to be especially big and bright. Big ones like this are always unexpected, always startling to witness, and always a thrill.