U.S. East Coast Bombarded By ... What?

gmr2048 writes: "Our local Fox affiliate is reporting a compact-car size metior may have hit north central PA Monday evening. CNN story here. Too bad I missed it :("

The loyal fjordboy writes: "At about 6:30 EST this evening, many meteors broke apart and headed south coming from Canada. I was able to witness the meteor flying overhead in Trout Run, PA and it was spectacular. There was an incredible bright flash and then a meteor with an incredible tail. A few minutes after it had left, a sound shook the ground and buildings in the vicinity. It even set off some car alarms in the parking lot." Anyone else out there see this in person?

Comments

Slow sound?

[Eric Sharkey]

Sonic booms were heard up to 100 miles from the meteor's path ... would have been traveling between 100 mph and 200 mph.

Wow. Anything that can travel less than 200 mph and still make sonic booms is worth a headline.

Where do they get these reporters? Slashdot?

Re:Slow sound?

[Moofie]

Not so. Terminal velocity derives from the force balance of an object with (more or less) zero kinetic energy falling towards earth, and the drag force that object encounters.

Essentially, your energy balance looks like this:

PEinitial=KEfinal+Edrag

where Edrag is the total energy lost over the fall due to drag (IE integrate the drag over the distance fallen).

PEinitial is a function of height above ground (OK, fine, distance from the center of the earth, but it's a difference so your zero point doesn't matter...you get the idea.)

KEfinal is equal to .5*M*V^2, where M is mass and V is the final velocity of the object. Since drag varies as the square of velocity (for a relatively flat plate normal to the free stream) your velocity goes up to some rather modest figure, and then stabilizes at the so-called terminal velocity.

A meteorite is coming into the atmosphere at Ludicrous Speed, and basically doesn't give a fuck about what the atmosphere thinks about it. : ) The meteorite ablates, producing a VERY impressive light show, and makes shock waves in the atmosphere (which do slow it down rather quickly)...but it never slows down to a piddly 200mph.

Also note that 200mph is a not-bad estimate for terminal velocity of a person, but since a rock has substantially higher mass per surface area (wing loading, if you will) the terminal velocity will be much much higher. (Basically, weight force is larger compared to drag force).

Now you are enlightened. : )

Re:Slow sound?

[Restil]

Meteors typically enter the atmosphere at 20-70 miles per SECOND, not hour. Terminal velocity doesn't really apply to meteors, the meteor hits the ground or burns up long before it can slow down enough to reach terminal velocity.

However, 100-200 mph is probably not a typo for mps. For a rock (of any size) to be travelling fast enough to enter the atmosphere at that speed, it would have to originate from outside the solar system, since that speed is to fast to remain in any orbit of the Sun without escaping the solar system.

Therefore it is quite safe to say that the reporters are getting funny numbers from someplace, likely they just made it up, but THAT's never happened before, right? :)

-Restil

Re:Slow sound?

[imipak]

>Meteors typically enter the atmosphere at 20-70 miles
> per SECOND, not hour.
Correct. > Terminal velocity doesn't really apply to meteors, the
> meteor hits the ground or burns up long before it
>can slow down enough to reach terminal velocity.

Sorry, I'm afraid you are mistaken. It's true that the vast majority of objects entering the earth's atmosphere are vaporised long before reaching the ground - these are meteors, the familiar shooting stars. (You can normally see one or two meteors per hour on a good dark night.)

Meteorites are objects sufficiently large that they don't completely vaporise. Instead, they become bolides - fireballs - as it sounds like this one did. It's pieces of these objects that end up in museums , labs or collectors. Contrary to popular belief, these *DO* hit the ground relatively slowly - plenty hard enough to kill you if it hit you, but no faster than if it had been dropped from an aeroplane. They're also NOT red hot, glowing or smoking - they often feel cool to the touch immediately after impact. (The reasons are left as an exercise for the reader ;)

The things that leave dirty great holes in the ground, wipe out dinosaurs, etc, are way bigger, so big that they don't become fireballs before smacking into the earth. These *do* hit at 20, 30, 50 thousand miles per second.

Good references for such matters:

• http://medicine.wustl.edu/~kronkg/namn.html
• http://www.meteoritecentral.com/
• http://home.pi.net/~terkuile/meteors/dms.htm

(some of these may be a bit broken, it's been a few years since I was an active meteor observer - Google for 'NAMN' and 'IMO' (Int'l Meteor Org. Oh, and MeteorObs mailing list.)
--
"I'm not downloaded, I'm just loaded and down"

Zat vas just a varning shot...

[Linux Freak]

Ze next von, comradeskees, vill be pointed at ze capitaliste pigz at Adobe.

I saw it

[kaze]

I saw one, I was sitting on a stoop at 307 N 3rd in Philadelphia waiting for someone just looking around at buildings and the sky and to the NW this big fireball zoomed by; looked to be about a mile away - no sound. I hoped it was a meteor, but thought it might be a small plane or a burning fuel dump from a larger plane. It got pretty low so some of them may have hit. Real quick, just like a shooting star where if your looking the wrong place or blink you'd miss it.

Maybe it was aliens

[leucadiadude]

returning a previously stolen concrete PC.
(See previous /. story)

AC (Air Conditioner)

[andkaha]

CNN Washington Bureau Chief Frank Sesno was traveling in Pennsylvania and reported hearing "what sounded like a tremendous sonic boom" through the closed windows of his air-conditioned car.

It's a good thing they don't leave out any details that might turn out to be important...

Re:AC (Air Conditioner)

[quintessent]

Remember the effects temperature can have on sound. If it had been 3 or 4 degrees warmer, the "sonic boom" might have sounded more like a "duck" or "Michael Jackson" A careful reader would have noted this.

Also notice that the sonic boom seemed to go through the windows of their car. Had it been going through the transmission, now that would have been something.

Re:Not again...

[CodeMunch]

It's the next engineering trick. Instead of students hanging VW bugs from their bridges, we're tossing them from the arm. BEAT THAT! :P

--Clay

Ahh!

[Yoru-Hikage]

So that's where I parked the Pinto...! Man, my insurance company is going to kill me...

Re:a bright flash and then...

[NumberSyx]

Hey, just be happy it missed you

Are you kidding, how else am I suppose to get super powers. I mean the irradiated spider thing just doesn't work.

Jesus died for sombodies sins, but not mine.

Link to space.com story

[jgaynor]

Light on any impact details, but here it is from the boys who know:

http://www.space.com/scienceastronomy/solarsyste m/ meteor_eastcoast_010723.html

Shoulda seen it before they editted it back...

[DarkEdgeX]

CNN Washington Bureau Chief Frank Sesno was traveling in Pennsylvania and reported hearing "what sounded like a tremendous sonic boom" through the closed windows of his air conditioned 2001 Chevy Impala. Frank was also snacking on some trail mix at the time, and washing it back with some Lipton "Brisk" Iced Tea. Afterwards, Frank made a stop at the nearest rest area to "leak the lizard", in his own words.

Illegal aliens

[MarsCtrl]

"At about 6:30 EST this evening, many meteors broke apart and headed south coming from Canada."

Just another example on why we need tighter controls on our Canadian border. Keep the meteors in Canada, where they belong!

With apologies to HG Wells. . .

[oldbox]

And the deep, warm voice of Orson Wells:
"And now, we bring you live to Grover Mills, just outside of Trenton, New Jersey . . . "

radiobox