is a copy of an article, as
it was first published in:
Feb. Issue 2003, Volume 9 No.1
was later excerpted in FIREHOUSE MAGAZINE in May of
the same year.
It was originally titled: "Was it a Cow or a Comet" but "Meteorite
Magazine" wanted to change the name.
this was published I received several emails or more
information about meteors (NOT) starting fires. This
is included after the article reprint.
You may go directly there by clicking here.
It A Cow Or A Meteorite?
by Captain Mica Calfee
note: This is the charming story of a fire captain
who had a theory…
It started with a theory I had. As a 22-year veteran of the fire service I
had some credentials. I was a captain certified as a Master Firefighter, a
fire service instructor, a paramedic, and a state field examiner for firefighter
certification. I have a degree in fire protection and have taught classes on
a variety of subjects in my career. One of them was fire service history. Like
most Americans I knew of the great Chicago fire of 1871, but few knew of the
Peshtigo, Wisconsin fire 200 miles away that occurred on the same night and
claimed five times the number of lives. My theory came to me when I heard that
there might have been a fireball sighting the same night. Most historians give
no credit to the “Mrs. OLeary’s cow story. Could a fiery celestial
visitor have caused one or both of these fires? Thinking I may have discovered
the cause of one, if not both of these fires, I set about the task of trying
to publish my theory. I contacted several people in the scientific community
and began researching the field of meteoritics for answers. I was not prepared
for what I discovered. It seems that Hollywood was wrong! The odds of a meteorite
starting a fire any time or anywhere on Earth is virtually zero – or
so it seemed. But I persisted.
July 23, 2001 a bright fireball was observed passing
over the eastern United States from Virginia to Canada.
The event was accompanied by sounds of explosions that
shattered windows in Pennsylvania. The sound was that
of the object breaking the sound barrier as it entered
Earth’s atmosphere. There were additional reports
of fires started from the falling debris. Says Bob
Young of the State Museum of Pennsylvania, “One
of our planetarium staff was told that the little northern
Pennsylvania town of Trout Run was destroyed by the
impacting meteorite.” Moreover, there was a report
of a scorched cornfield in Lycoming County, Pennsylvania
and other reports of hot rocks being scattered over
a wide area. Were these reports factual? Could a meteorite
cause widespread fires?
With any spectacular event, the truth is often distorted. While this was reported
as a “meteor shower” by the news media, scientists disagreed. Based
upon the many reports, scientists concluded the event was a bolide or fireball
produced by a stone or nickel/iron body. “It was traveling perhaps 15
km/s or faster when it exploded in the atmosphere with a force of about 3 kilotons
of TNT”, said Bill Cooke, a member of the Space Environments team at
the Marshall Space Flight Center. It did damage structures that required them
to have been within about 100 km from the bolide when it was generating atmospheric
shock waves. “If this was a rocky asteroid, then it probably measured
between one and two meters across weighing approximately 30 metric tons”,
states Dr. Tony Phillips of NASA. With a bolide of that size there is little
chance of any of it surviving intact.
Damage exaggerations aside, from a fire service perspective, was there a danger
of fire? Like most people, I thought the July 23, 2001 event was something
rare, but it turns out that such occurrences are rather common. The Pennsylvania
bolide was the 76th fireball event in 2001, reported over North America. This
translates to about one every two or three days. Should we be concerned? Consider
the above two fires. We are all familiar with the Great Chicago fire. On October
8, 1871, a fire was reported that quickly grew to legendary proportions. The
statistics are as follows:
million in damage
many outside of the fire service are not familiar with
the Peshtigo, Wisconsin, fire. Peshtigo sits in the
center of a region about 200 miles due north of Chicago
that was destroyed by fire on the same night. It is
possible that the Peshtigo fire is not well known because
they did not have the benefit of the Chicago Tribune
to dramatize it. The loss at Peshtigo was enormous:
million acres of forest and prairie burned
towns totally destroyed Peshtigo; Sugar Bush; Williamsville
did these fires have in common?
occurred the same night.
raged out of control within minutes.
were very hot, fast-moving fires.
areas were experiencing abnormally dry conditions
occurred about the same time a large meteoroid
may have been observed entering Earth’s
real cause has been determined for either disaster.
(Despite the Mrs. OLeary’s cow explanation.)
fighters are taught that there are reasons for a fire
to be large and widespread within a short period of
time. These reasons can include several fires set in
multiple locations or a very intense ignition source.
There are many stories associated with the Peshtigo
fire that suggest multiple fire fronts. One such report
describes a large number of people headed for the river
thinking that they would be safe on the other side.
As they crossed the bridge they encountered people
coming from the other direction thinking the same thing.
A riot ensued on the bridge until it finally collapsed.
This suggests two fire fronts on opposite sides of
the river. In both fires, people had little time to
escape. People found themselves cut off from escape.
This is uncommon for open prairie but it does happen.
However, I have a hard time imagining a situation with
1500 people being cut off from escape unless there
are multiple fire fronts.
In order to determine if an object falling from space could have started either
fire we need to understand the thermal nature of these interplanetary wanderers.
We saw earlier that these objects are traveling at thousands of miles per hour.
The small particles associated with meteor showers are usually about the size
of a pea or smaller. None survive the fiery journey through the atmosphere.
When a stony or iron meteoroid enters the atmosphere it does two things. Its
surface heats up due to friction with the air and it begins to quickly slow
down. The heating causes the outermost millimeter of material to melt and slough
off. This is a process called ablation. As the meteoroid loses mass during
its flight it disperses its heat thus cooling the outer surface. Within seconds
the meteoroid slows to a speed where the air disperses more heat than is generated
by friction. Only the outer surface is heated at all. Stony meteorites are
poor conductors of heat and there is insufficient time to carry heat to the
interior. A freshly fallen meteorite is often cool if not cold to the touch.
There are reports of ice condensing upon the surface of meteorites as they
lay on the ground in warm conditions. Meteorites have actually been found on
the surface of snow or ice without any melting beneath. The meteoroid slows
down until it reaches terminal velocity where all of its initial velocity has
been lost and it falls by gravity alone. Depending on the shape and mass of
an entering meteoroid, its terminal velocity can vary between 200 and 400 miles
Some meteoroids do hit the Earth with such force that tremendous heat is generated
and even terrestrial rock is melted. Such meteoroids are very rare. For this
to happen the body would have to be many times larger than the July 23, 2001
fireball. Instead of 1-3 meters across it would have to be at least about 50
meters in size. As it strikes the Earth it would fold the layers of rock back
and leave a permanent crater. Hot sparks and molten rock would be ejected.
If it broke apart during flight, it would leave a crater field. An example
of such an event is located 10 miles west of Odessa, Texas. The Odessa crater
is just one of dozens of examples of large meteorite impact craters. The most
famous example is the Barringer crater which is 1280 meters across found on
the high desert in northern Arizona. By comparison, the largest Odessa crater
is only about 170 meters in diameter. Yet, even one that size would not go
unnoticed. The mass of the iron meteorite that struck the Earth at Odessa is
estimated to be about 70 tons. This would not produce a simple hole in the
ground that started some grass fires. This would be like a large bomb exploding.
Imagine a bomb that would create a 170 m wide, 30 m deep crater. It would take
a meteorite of this size or larger to be the ignition source of a major fire.
In order for an object to be this size when it impacts it would have to be
much larger when it entered the atmosphere.
The simple fact we must conclude here is that there has not been one credible
report of a meteorite starting a fire. When we consider all the evidence, we
can state that meteorites pose virtually no threat of being an ignition source.
If a large enough object gets through the atmosphere and strikes the Earth
with enough force to cause a fire then that fire would probably be a small
part of the problem. It is probably safe to assume that the only way an object
falling from outer space could have caused the Great Chicago Fire was if it
had frightened Mrs. OLeary’s cow into kicking over the fabled lantern.
Copyright© 2004 Mica Calfee or METEORITE MAGAZINE
Please contact for permission to reproduce anything on these pages.
The Author in the Odessa Impact Crater.
The fence posts, in the background, show the edge of the crater rim.
For more on this crater you may go to:
more information about meteorites and fires.
you might imagine I have received several emails and
comments about this article. There are a large number
of people who cling to the idea that meteorites are
hot enough to start fires. Some people believe that
at least some are hot.
is a NASA webpage on the subject: Meteorites
Don't Pop Corn!
was contacted by fire fighters who testified that “Old
Man Johnson’s barn was burned down in ’52
by a meteorite.”
But I also received emails from scientists who completely disagree with that
such person who contacted me was perhaps one of the
most qualified to speak on the subject. George Zay
was, at one time, the number one tracker and data gatherer
for the International
Meteor Organization. The IMO is the organization
that NASA checks with from time to time when they are
having questions about meteorite activity. When Mr.
Zay was not the number one collector
of data for the IMO, he was still in the top three,
in the world, for many
years. We traded many emails wherein he questioned
several of my statements and I would have to agree
with every one. He also agreed with my basic conclusion.
was co founder of North
American Meteor Network (NAMN) and an original
author of the NAMN Guidebook. Although he is retired,
several chapters still bear his name even after several
has also written “"Zay's Meteor Observing
Guidebook". This book has been read all over the
Mr. Zay has graciously agreed to allow me to reprint
some of his emails here. Where it was necessary
to show my original question or statement, this
red. I hope it’s not too confusing.
Zay questioned how I came up with some of my figures
about the frequency of bolides.
I responded with:
>> I know that hundreds of thousands of meteoroids enter the earth's atmosphere
all the time. But "big bolides", like the one over Penn. are rare.
The July 23, 2001 bolide was, according to what I read from NASA, the 76th of
2001, "OBSERVED OVER NORTH AMERICA in 2001". What criteria NASA was
using to describe or number it, I don't know. I am guessing that they are talking
about the spectacular kind that breaks windows. Since July 23 represents about
half the year I extrapolated that we can average about one "like this" every
other day over North America. This put it in terms to tell the average person
that they are much more common than most believe. If you consider that there
are perhaps 150 or more like this one just over North America, (big and widely
observed) and the relatively small percentage of the earth's surface N. America
occupies, I think that my simple math approaches your number too.<<
Zay: Yes...hundreds of thousands of meteoroids everyday.
I'm not sure on what grounds NASA is referring to when
they say it was the 76th seen over North America that
year. Believe it or not, I've found that NASA is relatively
weak in regards to it's expertise on meteor activity.
Maybe somebody in NASA took it upon themselves to numerate
reported fireballs? If anybody knows anything about
meteor activity, it would be the International Meteor
Organization that I once belonged to. In the past,
NASA has referred to this organization when a manned
craft was to be launched during a period of potential
meteor storm activity. There is a hierarchy to the
sizes of meteoroids that enters the atmosphere or in
space in general. Visualize an equal sided triangle
with the point on top...much like the old Fire Triangle.
At the very top you find very few of the very large
meteoroids...like the size of asteroids. And at the
big broad base, you will find millions of the very
small microscopic meteoroids. From the top down, you
will find more, but slightly smaller sized meteoroids
than the category above it.
mentioned that “friction” is not the best
word to describe the heating process. I responded:
>> Yes I used the word "friction" to describe the heating. That
was probably a mistake. This is somewhat of a simplification. (Make that a huge
simplification.) I know that it is the air heating up in front of the body. You
and I could spend time debating semantics. I know that you are absolutely correct
in what you say, but isn't heating due to compression a form of heating by friction,
(on a molecular level?)<<
Mr. Zay: Most people when they think a meteoroid heats up due to friction,
are thinking that the air flow is passing against the meteoroid itself causes
the heating. But this isn't the source. The source is compression of the air
in front of the meteoroid. There's an air pocket of a sorts in front of the
meteoroid that gets highly compressed and the heat is created then and there.
However, within this compressed air pocket on a molecular level, friction does
occur, but mostly between air molecules against other air molecules. There
is airflow passing across the meteoroid, but that isn't where most of the heat
comes from. When people report the various colors (particularly green and blue)
of a fireball, the colors are primarily due to the excitation of the various
atoms in the atmosphere and not the meteoroid itself. Green and blue comes
from the Nitrogen and Oxygen atoms for example. The colors from the melting
meteoroid itself are there, but in a faint state and are usually overwhelmed
by the colors from the atmosphere.
You said >>However, I have a hard time imagining a situation with 1500
people being cut off from escape unless there are multiple fire fronts.<<
During wildland fires out west, area ignition is a common occurrence. I'd expect
it during very dry and windy conditions.
I kind of skipped over this. I would have liked to
have gone back and talked about normal fire behavior.
But that is not something a meteorite publication had
a big interest in. There WERE several separate fires
that night. But that does not mean anything. Yep, happens
all the time in California.
was published in "Firehouse Magazine" was
a little different. I sent them the original article,
with additions, and they talked more about the fires
in an earlier article. The same month (March 2003)
that my article came out in Meteorite, an article came
out in FH about the Peshtigo Fire. In it the author
mentioned the possibility of a meteorite starting the
fire. He said that "some astronomers point out
that there was a meteor shower that night and suggest
this as a possible cause." I jumped on that.<<
Mr. Zay: I'll let you in on a secret ...technically speaking, on any given
night there is some kind of meteor shower activity going on. There are literally
hundreds of meteor showers listed. Only several are usually heard about, because
they can be easily noticed...such as the Perseids, Leonids, Geminids etc. The
rest are known as minor showers. That is their shower members are few with
a ZHR (Zenithal Hourly Rate) under 3. For the most part, the only way to determine
if these minor showers are related or not, is to plot them onto star charts
and note various recognized characteristics. I use to routinely do this and
got to know the sky very well. If any astronomer suggests a meteor caused a
fire somewhere, he might as well be reading tea leaves. Most astronomers don't
know squat about meteors, but they can tell you volumes about planets, stars
and galaxies. There is an air of arrogance amongst a lot of astronomers that
studying meteors is beneath them. It seems too easy and thus they assume more
than they should.
I simplified the heating process by putting it terms
of "time v. very cold rock." If an X kg rock,
near 0 degrees K is exposed to heat for a few seconds,
regardless of the heating OR "cooling" process,
it will not be heated to the (very cold) core. I probably
was trying to say that it is not being "exposed" to
heat for a very long time due to (A) The short time
it is actually generating heat, and (B) the fact that
what is heating up is not staying in contact with the
body for very long. Most people do not understand how
long it takes to fall to earth also. You and I know
that the object phosphoresces for a few seconds and
then falls for perhaps minutes, in many cases. I think
that people believe that an average everyday Leonid
meteorite hits the surface just after it stops glowing.<<
If it weren't for the ablation process, there could be room for the validity
of a meteorite reaching the ground hot. But ablation is there with every meteorite
dropping meteoroid.... except for the micrometeorites. Micrometeoroids (particles
the size of smoke or smaller) heats up when entering the atmosphere, but re-radiates
the same heat back into the atmosphere almost as fast as it is produced. Thus
they don't burn up and slowly drift to the earth as dust.
Yes, most people think that when a meteorite hits the ground, it is red hot
or something like that. There are two primary sources for meteors...comets
and asteroids. Most meteorites that reach the ground are from asteroids.
A few rare one's are from the moon and Mars. There is no authenticated meteorite
that has a comet for a parent. So all the named showers such as Leonids, Perseids,
Lyrids and even the minor showers, are material from a comet. There are a couple
exceptions, such as the Geminids, but it is believed that their parent bodies
are from a burned out comets
a previous email Zay said>The object that caused
the 1908 Tunguska incident in Siberia was most likely
a small stony asteroid over 150 feet in diameter. It
was too structurally weak and thus exploded about 7
miles over the earth surface. When it hit the thicker
layers of the atmosphere, it was much like a dirt clod
hitting a brick wall...but a lot more violent with
a lot of heat energy released.
is what I thought too. I mentioned Tunguska in the
original article. But the editors made me take it out.
Partly because of length and partly because of controversy
I guess. The general thought now is that Tunguska may
have been a comet and not something stony. http://www.orc.ru/~azorcord/page_sbs.htm
It will probably be disproved tomorrow. Who knows?<<
Zay: There seems to be more evidence that the Tunguska object was of Asteroidal
parentage. We have military satellites up to search for atomic bomb testing
since about the late 1960's or early 70's that also picks up large meteors
such as the one you wrote about. These satellites allow determination of solar
orbits and thus where they came from. These large meteors are all from the
asteroid belt and often explode because of the pressure difference and weak
structure of the object. There are roughly 12 per year worldwide, all relatively
small...about 1/2 to a couple kilotons in explosive power. They explode just
like the Tunguska object did. Think of the pyramid I mentioned earlier. You
will find fewer of the big objects, but more of the smaller ones. The 12 per
year is the rate for the 1/2 to couple kilotons of explosive power objects.
The Tunguska object produced about 40 megatons. Based on the pyramid, we are
probably looking at that representing the rate for that size...maybe every
300 to 1000 years? There should be more frequent rates for slightly smaller
objects than Tunguska, but less than the size detected on an annual basis.
tried to cover all this by saying that fires CAN be
caused by objects hitting the earth BUT any object
big enough or traveling fast enough to cause a fire
would not go unnoticed and the resulting fire(s) would
be the least of our problems.<<
Zay: Most definitely. :o)
- Near the Odessa Crater there are five or more, smaller craters.
One is as small as 10 meters in diameter. How would you explain this AND what
effect on the planet / terrain do you think one like this would have?<<
Zay: When there are multiple craters fairly close such as with the Odessa crater,
this means that the meteoroid broke up just before impact. If it had broke
up higher up, the larger objects will be found further downrange from the smaller
ones. We are talking several or more miles here. The bigger pieces have more
momentum energy intact than the smaller pieces. I also point out that most
of what we are seeing phosphoresce is not the glowing object. It is the air
Actually, when we see the glowing streak or trail (Known as Persistent train),
it is not heated air. It is that the air molecules are given a big boost of
energy that causes them to ionize. They almost immediately on a molecular level,
drop back down to a lower energy level. When this happens, the atoms will emit
a certain frequency of light. This streak can be quite wide. For example, if
something like a marble was an entering meteoroid, the glowing train it produces
will be about 3 or 4 feet wide at least. It's velocity will also be a determining
factor. Again, let's say a rock about a foot in diameter was a meteor...It's
train will be about a 100 feet wide. The meteoroid has imparted all it's energy
into a bunch of air molecules in chain reaction fashion. To an observer on
the ground, it might appear the width of a finger at arms length, but in reality
it could be about 100 feet in diameter.
>> We can't SEE lighting. We
see the super heated air channel the lighting is creating.
Is this similar?<<
Zay: Yes and no. Here the superheated air is ionized, but from electrostatic
causes. With a meteor, the air is mainly being ionized from the mass and velocity
of an object. This energy is being absorbed by air molecules.
know. I believe the minor shower that would have been
that night might have been the "Draconids".
I pointed out that there is a "shower" virtually
every night and mentioned the Draconids in my original
article. This was edited out.<<
If I was going to try to pin it on a shower, the Draconids would have fallen
on the right date. But this no doubt is just a coincidence that causes people
to try to marry unusual happenings together.
it fair to say that the mass of our planet increases
by tons everyday?<<
At least hundreds of tons daily....mostly in the form of invisible micrometeorites.
long does it take micrometeorites to "slowly" drift
Zay: Anywhere from 24 hours to 3 weeks.
a couple definitions:]
1) Meteoroid: An object in space with it's own orbit around the sun.
2) Meteor: A phenomenon of light observed from the passage of a meteoroid thru
the atmosphere...Not an object.
3)Meteorite: Any part of a meteoroid that has survived the passage thru the
atmosphere to land on the ground. I personally include what's left of the meteoroid
after passing thru the light phase and is in the process of falling to the
ground as a meteorite also. Some people don't, but the die is cast at this
point and nothing changes physically to it while free falling.
have witnessed a successful re-entry of the space shuttle.
(as well as an unsuccessful one.) How do meteorite
trails / falls differ?<<
Zay: Here's a rule of thumb to keep in mind...If what looks like a meteor takes
about 2 minutes to cross the sky...It's a re entering satellite of some kind.
If it lasts generally less than 30 seconds, it's a meteor of some kind. Some
fireballs last a little longer than 30 seconds, but very few and I don't recall
hearing of any lasting 2 minutes. The only one close to that was the great
fireball of 1972 that was a near miss...It lasted 105 seconds and never hit
the ground. It just skimmed the upper atmosphere and kept on going. If it had
hit the ground, it would have been a whopper of a hit...maybe end up being
something like what made the Odessa crater. Montana and Wyoming were probably
lucky it didn't make an air burst or we might have had our own mini-Tunguska.
is a photo of Comet Hale/Bopp taken by George Zay.
It includes the image of a sporadic meteor.
It was taken on March 6, 1997, from Descanso, Calif. USA.
time-to-time meteorites have struck man-made objects
such as houses, roads, cars, and even a mailbox (Claxton,
1984), humans (Sylacauga, 1954) and cows (Valera, 1972)!
Here is a listing of meteorites that have hit Humans, animals and/or man-made
There are dozens of impact structures in North America. Several are in Texas.
To see where all the world's impact structures are, check out.
information on why meteorites are cold can be found
in Phil Plait's book.
Misconceptions and Misuses Revealed, from Astrology to the Moon Landing 'Hoax'"
about the Chicago Conflagration