[meteorite-list] Fireballs & Optical Delusions (was, "Re: Bright Meteor Seen Over New Hampshire")

From: meteorites_at_space.com <meteorites_at_meteoritecentral.com>
Date: Thu Apr 22 09:44:44 2004
Message-ID: <20010331180228.23360.cpmta_at_c000.snv.cp.net>

On Sat, 31 March 2001, Robert Verish wrote:

> I continue to find people who witnessed the SoCal
> Fireball of 2001March25, 8:20PM PST. Tonight over
> dinner an acquaintance described what he observed from
> his residence on top of Rose Hills near Whittier, CA.
> To him the fireball appeared to be "a very bright
> white color until near the end of its flight where it
> turned an ever deepening shade of yellow." He
> insisted upon this following observation. "I saw the
> end of the fire ball's flight where it just sputtered
> and then promptly extinguished itself. And when this
> happened it was already down below my horizon,
> somewhere between Palos Verde Hills and Hermosa Beach,
> so this thing must have extinguished itself right
> above Torrance!"
> When I tried to explain to him that many observers
> experience an optical illusion when they see a
> fireball reach its retardation point, and that when he
> saw his fireball extinguish it was by then, probably
> 200 miles away and around 20 miles above the Pacific
> Ocean.
> He said, "That's impossible! You've got to be wrong
> about that. I SAW it BELOW the horizon!"
> That's when the delusion begins.
> Bob V.

Yes, and a delusion-illusion it is. I had a long and difficult argument with a person who read my statement at http://www.geocities.com/meteorite_identification where I maintained that meteors do not burn to the ground and when they do they explode like atomic bombs and create huge craters. He countered and wrote, "I know what I and my five friends saw-- the meteor hit just about a mile away and burned all the way to the ground."

I told him "if that was so-- you would not be writing me about it-- instead I would have heard of your deaths in the papers."

He ended calling me an "educated fool" and even after I explained in detail the physics behind it still he maintained still that "I and my friends saw it burn all the way to the ground, and the pieces were no farther than a mile away."

I told him to "Go out and find those pieces and get back to me with the proof. If such were found-- then I would revise my "educated fool" 'opinion.'

The Hollywood movie image of meteorite falls is hard to die. But the effect of seeing them burn all the way to the ground might be an illusion caused by persistence of vision. That is, when a fireball is seen to streak across the sky, its bright light burns its path into the retina (just like a flash bulb does) and then, because it is traveling and the eyes follow it-- when it does burn out above the horizon, or down to, the eyes continue in the path and extend the burned image so that it appears to be below the horizon.

Thus the myth is maintained, and what they are reporting is exactly what they saw, but not what actually happened.

Steve Schoner, AMS

> --__--__--
> From: Ron Baalke <baalke_at_zagami.jpl.nasa.gov>
> To: meteorite-list_at_meteoritecentral.com
> (Meteorite Mailing List)
> Date: Fri, 30 Mar 2001 09:04:03 -0800 (PST)
> Subject: Bright Meteor Seen Over New Hampshire
> http://www.zwire.com/site/news.cfm?newsid=1599214&BRD=1652&PAG=461&dept_id=12530&rfi=6
> Meteor Seen In City's Skies
> Kimberly Phillips
> Register Citizen (New Hamsphire)
> March 29, 2001
> Could it happen in Torrington?
> Glenn Carlson and his wife Sondra were traveling home
> from New Hampshire last weekend when they saw
> something bright streak across the sky. In the heavens
> above Route 8 southbound, the South Kent couple saw
> what they
> identified as a shooting star.
> The pair admired the glow then noticed it's light
> flicker, extinguish momentarily, and bound toward
> Earth eventually landing in a location between TJ
> Maxx, O&G Industries, Route 8, and Charlotte
> Hungerford Hospital.
> "It didn't like explode or anything," Glenn said
> Wednesday. "As it got closer (into the Carlsons' view)
> it kind of flared up and it kind of blacked out."
> Glenn said he was certain the object wasn't a bottle
> rocket or any mysterious visitor from outer space,
> merely a meteor speeding wayward through the
> atmosphere.
> "It was pretty neat," Glenn said.
> Susan French, vice president of the board of trustees
> for the Dudley Observatory in Schenectady, N.Y. and a
> star party coordinator for the Albany Amateur
> Astronomers Club, said the Carlsons indeed might have
> seen a meteor.
> The only thing, she said, is a meteorite, once it
> hovers about 12 miles above the Earth, extinguishes
> itself entirely and could land anywhere at anytime. So
> pinpointing an exact location from a streak in the sky
> would be nearly impossible.
> Most people identify fallen meteorites if the chunk of
> space rock hits something, such as a house or a car,
> or if a person stumbles upon something strange in a
> wooded area, French said.
> "There always are meteor showers," she continued.
> "There's a good chance he saw a meteor."
> A meteor, or shooting star, rapidly crosses the sky in
> about 15 seconds, whereas a satellite or an airplane
> takes much longer, French explained.
> And this time of year is ripe for meteors, as the
> March showers are now coming to an end.
> The only thing about which French was skeptical was
> the height the Carlsons said they saw the object.
> Generally, 60 miles in the air is when people see
> the burning rocks.
> But then again, some could say it might have been
> something other than a meteor.
> --__--__--
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Received on Sat 31 Mar 2001 01:02:28 PM PST

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