STRONG MAGNETIC FIELD DETECTED FOLLOWING
A SIGHTING OF AN UNIDENTIFIED FLYING OBJECT
by
Bruce Maccabee (c)B. Maccabee, 1994,2000
(This paper was originally presented at the American Physical
Society meeting in April, 1993 [Bulletin of the American Physical
Society, Vol. 38, pg 1041, 1993] and published in the Journal of
Scientific Exploration, Vol. 8, pg. 347, 1994.)
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THE SIGHTING
Perhaps some UFOnauts have magnetic personality. Anyway, one UFO
appears to have "left behind" a strong magnetic field. This paper reports
the discovery and significance of that field.
On Friday, Sept. 11, 1992, at approximately 6:20 PM Mrs. A
(name confidential; she holds a high-level position at a bank) was entering
the driveway at her home in Gulf Breeze, Florida when she saw to the
northeast, over the roof of her house, an unusual round object rise upward,
move to the right a short distance while flipping over (see Figure 1) and
disappear in the clear sky.
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It appeared brownish-grey at the top and bottom with a pinkish-red line
around its circumference. The center of the bottom seemed to be glowing.
The object was at some distance and apparently had risen upwards from behind
her house where there is a lawn, a pond and trees. The total duration of
the sighting was several seconds. Within an hour or so the witness told her
husband, J, (who also wishes anonymity) about the sighting. Several hours
later he contacted two local UFO investigators, Bland Pugh and Bruce
Morrison, both members of the Mutual UFO Network. (Note: the MUFON
investigators were quite well known in the area of Gulf Breeze and
Pensacola, Florida because of the numerous newspaper, radio and TV stories
about sightings in the area that started in late 1987 and continued into
1992.) They agreed to visit the site during the afternoon of the next day.
THE SEARCH FOR A MAGNETIC FIELD
There were thunderstorms in the area and it rained for a while late
Friday night. The next morning J used a transit to determine Mrs. A's
sighting line direction from her observation point in the driveway. He then
decided to search the area behind the house to determine whether or not
there was any trace of magnetism left by the UFO. He decided to search for
a magnetic field because many years before he had had a UFO sighting which,
in his opinion, involved a strong magnetic field.
One night in 1973 a bright UFO had passed over his car and afterward
the gauges on the dashboard, including the non-electrically operated oil
pressure gauge, all pointed roughly toward the steering column, a shaft of
magnetizable iron. He believed at the time that a strong magnetic field
associated with the UFO had magnetized the steering column causing the
needles to point toward it. At that time he had no instrument to confirm
that there was a magnetic field. But in 1992 he had a very sensitive
device, a flux gradient magnetometer or "gradiometer" (model GA-52,
manufactured by the Schoenstedt Instrument Corporation (reference:
Schoenstedt), which he has used during the last ten years to search for
buried oil well casings (iron pipes) as part of his work.
THE FIELD GRADIOMETER
The gradiometer is a battery powered device which has a cylindrical rod
(pipe) called a "wand" that is attached to a cylindrical case (see Figure
2).
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In the wand are two rigidly mounted fluxgate magnetometers (Primdahl,
1979) with their axes oriented along the rod and which are spaced about 51
cm apart. Each fluxgate is sensitive to the component of the magnetic
field, B, along the axis of the wand. The electronic circuitry in the
cylindrical case creates the magnitude of the difference in the component B
values sensed by the two fluxgates. (The circuitry does not determine which
way the field is pointing along the axis, i.e., it does not distinguish
between "forward or backward" along the axis of the gradiometer.) This
difference, divided by the spacing, is the magnitude of the gradient of the
field along the direction of the wand. Hence the device is called a
gradiometer.
The electronic circuitry also generates an audio tone that drives a
loudspeaker in the cylindrical case. The most important characteristic of
the device for purposes of scientific research of magnetic fields is that
the frequency, f, of the tone increases monotonically with the magnitude of
the gradient. Furthermore, over a reasonably wide range the frequency,f, is
roughly proportional to the gradient: f = K times(the magnitude of the
difference), where K is the calibration constant.
The gradiometer is a rugged field device that was designed for locating
magnetic field "sources" such as buried iron objects. (Note: here the term
"source" is applied to any object or material which either has its own
magnetic field, such as a magnet, or which distorts the earth's field in the
vicinity of the object, such as a piece of iron.) A field source could be a
magnetized material or a ferrous (permeable) but non-magnetized material.
It can detect non-magnetized ferrous materials because they distort the
earth's field and the gradiometer detects the field gradient caused by the
distortion. For example, a representative of the Schoenstedt company told
me that at its most sensitive setting it could detect a piece of iron the
size of a manhole cover at a distance of about seven feet.
The gradiometer is typically operated in the following manner: the
operator holds the wand where it joins the cylindrical case and, while
walking over the area to be searched, he "waves" it around, thus moving and
rotating axis of the fluxgates. At each location as he moves the operator
searches for the location and direction of the wand where the frequency is
the highest. When this is found the operator moves a short distance in the
direction the wand is pointing and again waves it around to find the highest
frequency. If the operator is now closer to the source the new maximum
frequency should be higher than the previous maximum frequency. A large
buried piece of metal can be found in this way because the wand points
generally in the direction of the source of the field gradient, thereby
leading the operator toward the metal. However, at many locations the
gradient may actually point slightly away from the direction to the source.
For example, at most locations in the field of a simple dipole source the
maximum gradient points several degrees of arc away from the direction to
the center of the dipole. The operator can compensate for this by doing
enough of an area search to localize the area where the frequency is the
highest. This localized area contains the source of the field. The same
mode of operation can be used to locate any source of magnetic field,
whether underground or not.
DISCOVERY OF THE MAGNETIC FIELD
J began his search by following a footpath that leads around the west
(left) end of the pond and then eastward on the north side the pond (see
Figure 3 which is only approximately to scale). He was continually waving
his gradiometer in various directions to the left and right while pointing
it toward the ground and also upward.
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As he approached the east end of the pond he began to notice an
increase in frequency. He subsequently determined that the frequency was
highest when he stood on the shore of the pond, approximately at the
location of the triangle in Figure 3, and pointed his instrument upward and
over the pond. He believed that either he was detecting a "magnetic cloud"
in the air over the pond or else his instrument was not operating correctly.
He checked the operation of his instrument at a location a considerable
distance away from the magnetic field and convinced himself that there was
nothing wrong with the gradiometer. He then continued his search around the
pond and discovered an area where he obtained the highest frequency when he
pointed the wand straight upward or nearly so. This area, which seemed to
him to be beneath the source of the field, was under some pine trees on the
south side of the pond (see Figure 3), about 60 feet (18 m) from where he
first detected the field. His impression was that the source was actually
at or above the tops of the trees.
GRASS CIRCLES DISCOVERED
He also noticed, while looking over the 4 to 5 foot deep pond, that
there were three circular areas of depressed pond grass at the bottom
(Figure 3; the circles are not to scale). He had been fishing there several
days earlier and had not seen any circles. Subsequently, after plotting the
locations of the circles and the strong magnetic field on a map of the area
he found that they were roughly in the direction of the sighting line of the
witness and about 200 feet (60 m) from her location in the driveway (Figure
3).
THE INVESTIGATION
Several hours later the two MUFON investigators (Bruce Morrison and
Bland Pugh) arrived with a video camera and a Geiger counter. Mr. Pugh made
an area search with the Geiger counter and found no clearly elevated
readings. J showed them the circles at the bottom of the pond and
demonstrated the operation of the gradiometer. Mr. Morrison used a video
camera to record the way J operated the gradiometer as he searched the area
for the presence of magnetic field sources. The video camera also recorded
the audio pitch of the gradiometer as J waved it around at various
locations. I subsequently determined from the videotape and from my own
experiments with a nearly identical gradiometer that J operated it in a
completely normal manner. A simple experiment carried out later by J at my
request provided a calibration of the gradiometer and proved that it was
operating normally.
Mr. Morrison first recorded J operating the gradiometer on the north
side of the pond (triangle location, Figure 3) looking southward toward the
clump of pine trees. As J moved the gradiometer from side to side the audio
pitch was maximum when the wand was pointed somewhat upward (20- 30 degrees
of elevation) and generally in the direction of the trees which were about
60 feet (18 m) away across the pond. This suggested to J and the
investigators that the source of the field was above the lake or perhaps at
or above the treetops on the other side. As the gradiometer rod was turned
away from the direction of maximum frequency (maximum gradient), i.e.,
rotated to the left, right, upward or downward, the frequency decreased
considerably. The maximum pitch was at such a high frequency that J offered
his opinion, based on using the gradiometer under many conditions for about
ten years, that the response of the gradiometer was comparable to what one
would get by putting the gradiometer very close to a large piece of iron or
steel.
The investigators then walked to the clump of pines. There the
videotape shows that the highest frequency recorded, higher than at the
location across the pond, was obtained when the gradiometer was vertical or
nearly vertical under the trees. As J walked away from the clump of trees
in various directions the maximum frequency diminished indicating that he
was moving away from the field source. (Note: there was no boat available
at the time, so a search was not made over the water.) A search of the area
failed to turn up any source of field other than the source which seemed to
be at, or above, the treetops.
When J was across the pond from the trees and pointing the gradiometer
toward the direction of maximum frequency the audio pitch of the gradiometer
was not perfectly steady. Instead, it fluctuated rapidly by small amount in
pitch ("warbled") at a roughly constant rate of about 8 - 12 Hz in a manner
similar to a lightly modulated FM signal. (FM stands for frequency
modulation in which a "carrier wave" of relatively high frequency is caused
to change frequency slightly, usually a few percent, at a rate determined by
a much lower modulating frequency.) This warbling was also apparent when
the gradiometer was under the trees, where J called the attention of the
investigators to this unusual effect. Subsequent experiments with a magnet
(see below) created greater gradients and higher frequencies than were
obtained under the trees, yet there was no "warbling" of the audio tone
during the experiments. The warbling suggests that the magnetic field was
pulsating slightly (changing in amplitude and/or direction) at a rate around
10 Hz.
While the investigators were under the trees Mr. Morrison pointed his
camera upward and videotaped the treetops and the clear blue sky. Nothing
unusual was seen in the sky or on the trees. (Recorded on the videotape is
a discussion by investigators in which they speculate as to whether or not
the source of the field, assumed to be the UFO, was still there but
"cloaked" so as to be invisible.)
J repeated the area search the next day. He reported that the
gradiometer had a slight response only under the trees, indicating a
considerable decrease in the magnetic field gradient. Unfortunately there
was no one to record these measurements of the magnetic field.
On Sept. 14, three days after the sighting, the MUFON investigators
returned to the area and videotaped J with his gradiometer standing under
the same trees where, two days before, the audio tone was very high. Now
the pitch was at a value that corresponds to "no detectable gradient."
On that same day the grass circles were measured and found to be about
11 ft (3.3 m) in diameter. A week or so later the investigators thought of
checking the magnetic field in the area with compasses at several locations.
All the compasses pointed north indicating that there was no large magnetic
anomaly in the area. (It is unfortunate that they didn't think to use
compasses on the day after sighting!)
DISCUSSION OF THE VISUAL SIGHTING AND THE CIRCLES
The sighting, although very brief, provided the witness with enough
visual details to demonstrate that the UFO was no conventional aircraft, nor
was it a bird, an insect or a piece of debris blowing in the breeze.
Athough the sighting did not provide much visual data for analysis, it did
provide an angular size which can be compared to the size of the circles if
the distance to the UFO is assumed. The witness estimated the angular size
to be about four times the diameter of the moon which corresponds to roughly
2 degrees or about 0.035 radians. If one assumes that the UFO had actually
risen upward from one of the circles just before the sighting and was
therefore about 200 feet (about 60 m) away, then the actual diameter of the
circular object was nearly 7 feet (2.1 m). This is four feet less than the
measured diameter of the circles. However a rather small increase of 1.1
degrees in the estimated angular size, making it about 3.1 degrees or six
times the diameter of the moon, would make the calculated size equal the
circle diameter. It certainly is reasonable to assume that the witness
could have underestimated the angular size by this small amount, and hence
we may conclude that the visual sighting is consistent with the size and
shape of the "circular evidence" at the bottom of the pond. Of course this
does not prove that the observed UFO made the circles, nor does it explain
the discrepancy in number: there were three circles but only one observed UFO.
The discovery of one or more circles in an area of a UFO sighting is
not a rare occurence, although generally such circles are found in grass or
grain growing on dry land. However, "saucer nest" circles which were
discovered after a UFO sighting on January 19, 1966 near Tully, Australia,
were in a swampy area. The reeds were bent below water level (Phillips,
1975; Story, 1980; Delgado and Andrews, 1989). Phillips (1975) and Delgado
and Andrews (1989) describe a considerable number of UFO sightings and
associated circular traces that occurred in various countries including the
USA, FSU (USSR), Canada, Australia, New Zealand and Britain.
ANALYSIS OF THE GRADIOMETER DATA
Although the UFO observation and the discovery of underwater circles
are noteworthy by themselves, the aspect which really makes this case unique
is the detection of the magnetic field gradient. This section presents an
analysis of the field gradient data.
The gradiometer is designed so that it generates an audio tone with a
pitch that is very nearly proportional to the magnetic field gradient, that
is, to the difference in the strengths (magnitudes) of the magnetic field at
two locations. The sensitivity of the gradiometer is adjustable. In order
to provide accurate gradient values corresponding to the frequencies that
were recorded by Mr. Morrison during the investigation it was necessary to
calibrate the gradiometer at the sensitivity level used during the
investigation.
At my request, J carried out an experiment which provided the data
needed for calibration. I provided J with a small (1" long) bar magnet of
known strength which had been calibrated with instruments at a Navy
laboratory. J placed the gradiometer and magnet on a horizontal board far
from any power lines or metal objects. He aligned the gradiometer wand in
the east-west direction to eliminate the effect of the slight north-south
gradient which is detectable with his instrument. He then aligned the axis
of the magnet with the axis of the gradiometer. He placed the magnet at
various measured distances from the end of the wand and tape recorded his
verbal annotation of the measured distances and the resulting audio tones.
The shortest distances used were 1" (2.5 cm) and 0" (0.0 cm) from the end of
the rod or about 2.6" (6.6 cm) and 1.6" (4.1 cm) from the fluxgate sensor
closest to the end. These produced frequencies which were much higher than
those recorded under the trees near the pond. At distances of about 2 feet
(about 60 cm) and beyond there was no detectable effect of the magnet.
Subsequently I calculated the magnituce of the magnetic field at each
fluxgate sensor for each distance of the magnet's center using the standard
equation for the field of a (small) bar magnet along its axis, B = Bo/z^3,
where z^3 is the cube of the distance, z, from the center of the magnet to
the sensor location and Bo is the effective pole strength which was
determined from the magnet calibration (1040 nanoTesla (nT) at 30 cm from
either end; see the Appendix). The difference in the field amplitudes at
the two sensors for any given magnet location was divided by the sensor
spacing, 0.51 m, to get the gradient as a function of distance. According
to the manufacturer, when the gradient is below 1,000 nT per meter (nT/m)
the frequency remains at a fixed minimum of about 65 Hz. I found that above
1,000 nT/m the relation between the audio frequency and the field gradient
is nearly linear, as illustrated by the calibration graph shown in Figure 4.
In the frequency range of interest to this investigation, 500 - 5000 Hz, the
use of a calibration factor of 12 (nT/m)/Hz provides an accuracy of 5% or
better.
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(A note on units and conversion factors. The MKS unit of magnetic flux
is the Weber (Wb), which corresponds to the number of "lines" of magnetic
force around a magnet or a loop of current. The field strength or magnitude
at any point is represented by the induction, called B, which is the flux
per unit area, Wb/m^2, called Tesla (T). Hence when B = 1 T the magntidue
of the field is 1 Wb/m^2. In the cgs system the area flux density is in
Gauss (G). This is related to the MKS value as follows: 1 T = 10,000 G =
1E4 G. ["E" stands for "ten raised to the power of__"] For small fields a
more typical unit is the nT = 0.000000001 T = 1E-9 T (one billionth of a
Tesla) which is also called "gamma." The magnitude of the earth's field at
the surface is typically about 5E-5T = 5E4 nT = 50,000 gamma which is
equivalent to 0.5 G.)
It is important to realize that the gradiometer does not measure the
actual value of the field strength at a point in space. To measure the
strength of the field one needs a device such as a rotating coil of wire
(with a voltmeter attached), a "Hall effect device" or a fluxgate
magnetometer that uses a single fluxgate rather than (as in the gradiometer)
the difference of two fluxgates. However, the gradiometer is much more
sensitive than the previously mentioned devices for measuring variations or
"distortions" of the local (earth's) magnetic field caused by the presence
of magnets or non-magnetized, but magnetizable, materials (e.g., iron).
A magnet or a non-magnetized piece of magnetizable material will
distort the local magnetic field over some distance from the piece of
material, just as a rock in a river distorts the flow of a uniform stream of
water. The presence of a magnet or a piece of magnetizable material in the
earth's field creates a field gradient which the gradiometer can detect.
A magnetic dipole consists effectively of positive (north) and negative
(south) magnetic poles separated by a small distance. (Similarly, an
electric dipole consists of opposite charges separated by a small distance.)
Such a combination of poles creates a characteristic dipolar "shape" of the
magnetic field as measured at distances from the dipole that are much
greater than the separation of the poles. A small bar magnet creates such a
field at distances that are large compared to the length of the magnet.
A loop of wire carrying a current is also a source of magnetic field, a
phenomenon which is used extensively in electromagnets, electric motors and
generators. At distances considerably larger than the diameter of the loop
the strength and direction of the magnetic field varies with position in the
same way that it varies in strength and direction around a magnetic dipole
provided that one imagines the axis of the loop (a line through the center
which is perpendicular to the plane of the loop) is aligned with the axis of
the analogous dipole. Hence it is common to refer to a circular loop
carrying a current as a "current dipole." The similarity between a current
dipole and a small bar magnet (dipole) provides a useful means for comparing
the strengths of magnetic fields from different types of sources. This sort
of comparison is made in this paper where calculated source strengths are
given in terms of the equivalent current dipole strength which is the
product of the current flowing in the wire times the area of the loop in
square meters: amp-m^2. (Note: a single turn loop is assumed.) This is
described more below and in the Appendix.
The first field measurement as made when J waved the wand around while
he was standing on the north side of the pond looking southward toward the
clump of pine trees. The maximum recorded frequency was obtained when the
gradiometer was pointed toward the trees and tilted upward at an angle of
20-30 degrees. The maximum frequency was about 1,500 Hz which, from Figure
4, corresponds to about 18,000 nT/m. As the gradiometer rod was turned away
from the direction to the treetops the frequency decreased considerably.
Next J walked to the clump of pine trees and again waved the wand around.
The videotape shows that when the gradiometer was under the pine trees and
pointed straight upward an even higher frequency, about 2,100 Hz, was
obtained. This corresponds to about 25,000 nT/m. When the gradiometer was
pointed away from the treetops the pitch was much lower, and, as J walked
away from the pine trees the maximum pitch diminished. Hence it appears
that he was closer to the source of the field when he was under the trees
than when he was on the other side of the pond. The upward direction of the
maximum gradient suggests that the source may have been at or above the tops
the pine trees. However, as I have pointed out before, the gradiometer wand
does not always point directly toward the source, so the source may not have
been over the trees, but instead over the pond adjacent to the trees.
(Note: the Journal referee of this paper pointed out that the
gradiometer does not distinguish between "backwards and forwards" along the
axis of the wand. Therefore, if J had made a measurement of the gradient at
only a single location then one would have to allow for the possibility that
the magnetic source was underground. However, the directions of the maximum
gradients were measured from two locations which are about 60 feet apart.
These directions intersect above ground rather than below the ground. Hence
I assume that the source was above the ground.)
Two days later J was recorded again standing under the trees pointing
the gradiometer upward and this time the audio pitch was around 65 Hz,
indicating that the field gradient had been reduced below 1,000 nT/m. (This
does not mean that there was no field gradient, only that there was no
gradient detectable by the instrument at the sensitivity used during the
investigation.)
DISCUSSION OF THE FIELD GRADIENT DATA
In the Appendix I have presented the calculation of source strengths
under the simplifying assumption that the source was a single-turn current
dipole as described above. This must be considered an extreme
simplification of the problem because a large (infinite) number of
configurations of magnetic sources (dipole and multipole sources) could
create any particular gradient at a particular location. The calculation
also assumes that the size of the source is much smaller than the distance
from it to the gradiometer (a "point" source), whereas the actual source
could have been be quite large compared to the distance. Nevertheless, this
sort of calculation allows us to compare field strength associated with the
UFO sighting with field strengths of known sources such as electromagnets,
permanent magnets and non-magnetized but magnetizable (permeable) materials.
For example, assume that the source was at some distance above the
trees. If this were so, then the measured field gradient at the location
across the pond, 18 m from the trees, could have been generated by a current
loop of strength 3.1E6 amp-m^2 (see Appendix), providing that the axis of
the current dipole was aligned with the axis of the gradiometer. This
current dipole strength can be interpreted in the following way: a 1 m
diameter loop, with an area of 0.78 m^2, could create the measured field
gradient at a distance of 18 m if it were carrying a current of about 3.1E6
amp. Other size loops carrying other currents could also be assumed, as
long as the product current-area was the same. For example, a 2 m diameter
loop has four times the area and needs only one quarter of the current to
produce the same field. (If there were more "turns" in the loop the current
could be divided by the number of turns.)
Assume, now, a 1 m diameter loop carrying the above current. At its
center the field strength would be about 5 T. This field magnitude is about
100,000 times greater than that of the earth and is comparable to that
inside the strongest magnetic materials (magnetic alloys such as ALNICO).
Alternatively, one might imagine that the field gradient was created by the
equivalent of a massive piece of magnetizable material. By comparison with
the magnetic signatures of Navy ships it was determined that the field
gradient measured at 18 m would be produced at a distance of about 18 m away
from either end of a destroyer-sized battleship (the distance would be
measured along the projected axis of the ship)!
A considerably different source strength can be calculated by assuming
that the source was at the tops of the trees, about 3 m above the
gradiometer, when J operated it under the trees. Assuming again that the
gradiometer was aligned with the axis of a hypothetical current dipole the
source strength is now found to be about 3.4E3 amp-m2. This dipole strength
is three orders of magnitude less than the previously calculated value
because of the z^4 distance dependence of the gradient (see Appendix) and
the much shorter assumed distance (3 m vs 18 m). Such a small source
strength could not create the field gradient that was measured on the far
side of the pond. Therefore one might assume that the actual source was
considerably higher than the trees and possibly somewhat over the lake.
Unfortunately there were not enough measurements made to allow even an
approximate reconstruction of the magnetic field. One could imagine many
(an infinite number) of configurations of magnetic field sources that could
have created the measured field gradients. Therefore the most significance
one can attach to these measurements is that a large magnetic field was
clearly present in an area where there should have been no such field.
To clarify the significance of finding such a large field, consider
the following facts: (a) wood is not ferromagnetic (it cannot be
magnetized); (b) while J was standing under the trees with his gradiometer
pointed upward and generating a high pitch on Sept. 12, Bruce Morrison was
videotaping the tops of the trees which were silhouetted against a clear
blue sky and the investigators could see nothing up there that could cause
such a field gradient; (c) if, somehow, the wood had been made
ferromagnetic by a UFO (an impossibility, according to the physics of
magnetic materials), or if the UFO had deposited a massive amount (hundreds
of pounds?) of some ferrous (i.e., containing iron) material on the trees
(no deposit of material was seen on the trees, however), then the strength
of the magnetic field should have been the same on the second day of the
investigation because ferrous materials do not lose their magnetism at
environmental temperatures (they do lose it at temperatures of many hundreds
of degrees); (d) there had been rain the night after the sighting, yet
there was no indication of magnetic sources on the ground, so no magnetic
residue had washed off the trees.
Although the gradient was large there was no observable effect on the
videocamera. A calculation of the field strength at the videocamera when it
was under the trees, assuming that the source was farther than about 10 ft
(3 m) away (at or above the tops of the trees) shows that the field from a
3.4E3 amp-m^2 source would have been 0.00003 T or less, which is much too
low to affect the videocamera mechanism or the videotape.
Hence we are left with a double mystery: (1) how did the field get
there in the first place, and (2) once there, why did it disappear?
DISCUSSION OF OTHER UFO SIGHTINGS WITH MAGNETIC EFFECTS
Anomalous magnetic effects have long been associated with UFOs. The
earliest magnetic effect report on record is that of Fred Johnson who was
prospecting near Mt. Adams on June 24, 1947. On that day, and only minutes
before Johnson's sighting, Kenneth Arnold, a private pilot was flying a
small plane about 20 miles west of Mt. Rainier in the state of Washington.
Arnold saw nine flat, shiny crescent-like objects fly southward past Mt.
Rainier (Maccabee, 1986; Story, 1980). Arnold last saw them as they
vanished in the distance near Mt. Adams, about 50 miles south of Rainier.
Arnold's sighting was widely reported in the press and gave rise to the term
"flying saucers." (Although the Air Force called Arnold's sighting a
"mirage," and others have offered similar suggestions, the fact is that
Arnold's sighting could not have been caused by atmospheric phenomena. It
has never been explained (Maccabee, 1986).)
Several weeks after the sighting Johnson told the Air Force and then
the FBI that he saw several of the objects fly overhead. He looked at them
with a telescope and estimated their altitude as about 1,000 ft (about 300
m) above him and their diameter at about 30 ft (about 9 m). Of particular
interest here, however, is Johnson's statement that, as the object passed
over, his compass continually oscillated from side to side (Maccabee, 1986).
Assuming that the "saucers" were the source of the magnetic field that
caused the compass to oscillate we can estimate the source strength in the
following way. Assume that a magnetic field with a strength roughly 1/5 of
the earth's field (i.e., about 10E-5 T) that oscillates in direction or
pulsates in amplitude (or both) could cause a noticeable oscillation of a
compass needle. For simplicity also assume that a flying saucer is
effectively a current dipole 9 m in diameter and that the compass was, at
least part of the time, at a distance of 300 m along the axis of the dipole
as each saucer flew over. Since 300 m is much greater than the radius, 4.5
m, Eq. 2 in the Appendix can be approximated as B = 2 Bo/z^3. Inverting
this equation and solving for Bo with B = 1E-5T and z = 300 m yields Bo =
135 T-m^3 which corresponds to a source strength of 1.35E9 amp-m^2. This
source strength can be created by a current of about 21 megamps flowing in a
loop 9 m in diameter. The field strength at the center of the loop would be
about 3 T. Of course, these very simplified calculations probably do not
provide us with the actual effective source strength of the saucers, but
they do demonstrate that the fields would have been very large to have
affected Johnson's compass from a distance of 300 m.
In the years following 1947 there were reports of UFOs affecting iron
items such as streetsigns and automobiles (Rodeghier, 1981). Researchers
have long felt that car-stopping events were associated with the presence of
large magnetic fields in the presence of UFOs, although evidence for this
has been indirect at best. Experiments have shown (Rodeghier, 1981) that
either a steady or a pulsating magnetic field can affect a spark coil in an
automobile ignition system. A steady magnetic field can saturate the
magnetic core of the coil and decrease the spark strength. A strong enough
field could kill the spark completely. A somewhat weaker field which is
pulsating at roughly the firing frequency of the automobile but is out of
phase with the firing can cause the engine to stall. The demonstrations of
the effects of magnetic fields on automobile ignition systems are
interesting, but they do not provide conclusive evidence that magnetic
fields associated with UFOs have stopped any cars.
Claude Poher, a French scientist formerly associated with the French
National Space Agency (CNES), studied sightings in France that occurred
during the October, 1954 "flap." He also studied magnetic field readings
at a geophysical research station located at Chambon-la-Foret (Hendry,
1979). Poher claimed that the strength of the magnetic field tended to be
larger during the flap, although Hendry (Hendry, 1979) has pointed out that
this does not prove that the increase was caused by UFOs since the earth's
magnetic field tends to fluctuate anyway. (The fluctuations are typically
of a magnitude around 0.0001 to 0.001 of the earth's field and are a result
of fluctuations in the "solar wind.")
Poher also claimed to find a correlation between the distance of a
reported object from the station and perturbations in the vertical component
of the magnetic field at the station (Hendry, 1979; Hynek and Vallee, 1975).
A graph of Poher's magnetic field data (Hynek and Vallee, 1975) has been
magnified, slightly redrawn and reproduced in Figure 5 for convenience in
the following discussion.
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Poher found that the strength of the perturbations seemed to decrease
inversely with the distance of a UFO sighting from the station (the greater
the distance, the smaller the effect). Unfortunately the closest distance
was still 30 km away so the mathematical relation that he derived from the
data was not well tested. Furthermore, although it was not pointed out in
the publication, the line that he drew through the data points shows an
inverse square decrease with increasing distance rather than the expected
inverse cube which is associated with typical dipolar magnetic fields. If
the data were really accurate, this could be considered to be evidence that
UFOs are associated with monopolar magnetic fields. The idea that there
might be magnetic monopoles is, so far as we know, only a theoretical
construct which symmetrizes the Maxwell equations of electrodynamics by
providing a monopolar source for magnetic fields which is analogous to the
source (electron, proton) of the monopolar electric field. All sources of
magnetic field of which we are experimentally aware are dipolar (or
multipolar) in nature. Hence I have drawn another line, which corresponds
to the inverse cube dipole field, through Poher's data. It is interesting
to note that the inverse cube decrease with distance does not fit the data
as well as the inverse square. However the better fit for the inverse
square should not be considered as valid evidence that UFOs are sources of
monopolar magnetic fields because range in distances is quite limited (one
would like to see data from ranges 1 - 10 km) and because the data points
are very scattered.
By projecting the inverse cube lines on Figure 5 "backward" to a
distance of 1 m from an assumed source one can show that the equivalent
dipole strength is about 1.5E13 amp-m^2 which is many orders of magnitude
greater than the previously calculated values. Since the magnitudes of
these source strengths are crucially dependent upon the accuracy of the data
points in Poher's graph, the numbers calculated here can be considered to be
no more than indicative of very strong fields associated with UFOs, assuming
that Poher was correct in associating these fluctuations with UFO sightings.
A visual observation by Wells Allan Webb (reported in _Mars, the New
Frontier_, 1956; reproduced in "The UFO Evidence," NICAP, 1964, R. Hall,
Ed.) may also be related to a magnetic field around a UFO. He reported that
on May 5, 1953 between 9:45 and 10:0 AM he was observing the sky near the
Yuma Air Force Base in Arizona. Beside the normal Air Force craft flying
around he also noticed, in the northern sky, "...what at first appeared to
be a small white cloud... the only one in the sky at the time." However, it
was not a cloud. It was at an elevation of about 45 degrees, initially, and
it moved about "30 degrees to the east" during the first 5 minutes of his
observation. It appeared "oblong with the axis in the horizontal plane."
Then, "it appeared to abruptly turn and travel northward; at the same time
it's oblong shape changed to circular section. As a circular object it
rapidly became smaller as if receding. While receding it did not lose any
of its apparent brightness. In about 30 seconds of this, its diameter
became too small for the author to hold in his vision."
What makes this sighting interesting from the magnetic perspective is
what Wells reported seeing through his polaroid glasses. He wrote, "The
author was wearing Polaroid glasses having a greenish tint and, as was his
custom when studying clouds, he took the glasses off and put them on at
intervals to compare the effect with and without Polaroid." During the
first 5 minutes or so of observation he noticed no special effects of the
polaroid glasses. However, after the object turned, "...several uniformly
spaced concentric circles appeared around the now circular object" when
viewed through the polaroids. "The circles were distinct dark bands which
enveloped the silvery disc. The largest of these circles was, perhaps, six
times the diameter of the central disc. When the writer removed the glasses
the disc remained but the concentric rings vanished. When the glasses were
put on again the rings reappeared. The writer repeated this several times,
each time with the same result. The rings with glasses on faded to
invisibility before the disc became too small to see."
So, what does this sighting have to do with a magnetic field? The
answer is the property of strong magnetic fields to cause substantive media
including gasses (air) to rotate the plane of polarization. Since Mr. Wells
was looking northward (roughly perpendicular to the direction to the sun) in
the morning, a sizeable fraction of light reaching his eyes from the clear
sky was polarized (hence the value of polarizing glasses, to cut glare by
reducing the amount of polaroized light). Polarized light passing close to
the object before reaching Mr. Well's Polaroid glasses could have been
effected by a magnetic field on the object. More specifically, the field
could have rotated the plane of polarization by varying amounts, with the
lowest amount being for light farthest from the object but which is still
within a strong field. As the plane of polarization was rotated by varying
amounts some light would pass the polaroid glasses (because it has been
rotated such that it aligns with the polarization direction of the glasses,
i.e., horizontal) and some would be blocked (not enough rotation or too much
rotation). Whether the polarized skylight was passed (bright ring) or
blocked (dark ring) would depend upon how close it passed to the object.
Because the rotatory power (Verdet constant) for air is very low the
magnetic field would have to be huge to cause this effect.
Turning to a different but related matter, many people have attempted
to detect UFOs using simple magnetic field sensors in the past. A typical
simple sensor is a compass with an optical system designed to detect any
motion of the pointer from its normal north-south direction, and to set off
an alarm. I am aware of no clear-cut successes of this approach to
detecting UFOs. On the other hand, sensitive magnetic field detectors that
might detect UFOs are not common items easily available to civilian UFO
investigators and very few, if any, have them available for sighting
investigations. I am aware of only one other magnetic site survey of an
area of UFO activity that is similar to the one reported here (Bruce Cornet,
private correspondence, 1993: Dr. Cornet, a geologist, has surveyed an area
of UFO activity near Pine Bush, New York, using a proton magnetometer.)
The success in detecting a field after the sighting reported here and
the past reports of apparent magnetic effects suggest that local UFO groups
in areas of continued activity, perhaps with monetary aid from national UFO
organizations, should consider purchasing these devices for use by trained
field investigators along with the standard equipment (cameras, video
cameras, sample taking devices, etc.).
CONCLUSION
Following a brief visual sighting of a disk shaped UFO an area search
was made. In the bottom of a shallow pond three 11 ft circles of depressed
pond grasses were discovered. An estimate of the size of the disk based on
the visual apparent size and the distance to the circles agrees reasonably
well with the size of the circles. An area search was made with a magnetic
field gradiometer. The search discovered locations of anomalously high
field gradient in the absence of known sources (large pieces of metal or
electric current carrying wires). Estimates of the magnetic source
strengths were made using the recorded gradiometer data (audio tones). The
source strengths were found to be quite large in a manner that is consistent
with estimates based on observed magnetic phenomena associated with other
UFO sightings. One major difference between this magnetic field detection
and other reported cases is that there was no UFO visually present during
the detection of the field, which was only detected many hours after the
sighting. This raises the question of whether or not a UFO actually was
present during the measurements but in some way made itself invisible, or if
the departing UFO in some way managed to leave a magnetic "trace" of its
presence many hours before. (Perhaps there were still a bunch of not-yet
decayed-or blown-away magnetic monopoles stuck in the treetops. :) )
I thank Mrs. A and the Gulf Breeze Research team members (Bruce
Morrison, Bland Pugh and David Holcomb) for providing me with information
needed to complete this analysis. I also thank J for having the presence of
mind to use his gradiometer during this investigation and for carrying out
the calibration tests. Finally, I thank the referees for helpful comments
on this paper.
APPENDIX
A "field" is a volume in space throughout which some quantity (or
quantities) varies in a consistent and measureable way. The magnetic field
varies in both magnitude and direction (i.e., it is a vector field) in a
volume of space around a magnet or around a loop of current. As virtually
any textbook on electromagnetic theory (e.g., Scott, 1959) shows, the field
of a magnetic dipole (or an electric dipole), because of its rotational
symmetry about the axis of the dipole, can be represented in vector notation
most simply by using cylindrical coordinates with the z axis along the axis
through the center of the magnet or perpendicular to the plane of the
current loop. The other two axes, x and y, are replaced by new axes which
are the radial distance, r, from the center of the dipole, and the angle, a,
between r and the positive z axis. The equations for the radial and angular
vector components of B, Br and Ba, are
2Bo cos(a) Bo sin(a)
(Br,Ba) = ( ----------, ----------) 1)
r^3 r^3
where the magnitude of the field is given by (Br^2 + Ba^2)^1/2 and r is
assumed to be much larger than the dimensions of the source of the field
(much greater than the length of a magnet or the diameter of a current
loop). In this equation Bo in T - m^3 is given by (1E-7)MSL if the source
is a bar magnet of magnetization per unit volume M (amp/m) with cross-
sectional area, S (m^2) and length, L (m), or Bo is (1E-7)IS if the source
is a current loop (a single turn) of area S and current I (amp). Figure A1
illustrates the coordinate systems for the two types of sources.
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If the source is a current loop a more correct equation for the field
along the z axis where a = 0 is
2Bo
Br = ---------- 2)
(z^2+R^2)^3/2
where R is the radius of the loop and Bo = (1E-7)IS.
Along the z axis sin(a) = 0 in Eq. 1 so there is no angular component
of B: B points either directly toward or away from the center of the source
at all z values. Comparing Eq. 1 with Eq. 2 we see that r has been replaced
by z. When z is much greater than R the equations are essentially equal.
The simple dipole model can be used to calculate the equivalent source
strength, Bo, from the gradient measured by J's instrument if the distance
to the source is known or assumed. The measured gradient of the field is
the derivative of B along the axis of the wand. In terms of the dipole
model it can be shown that (by far!) the simplest direction to take is along
the z axis (i.e., assume that the wand axis lies along the z axis). Also
assume that the field gradient is measured at a distance far from the source
(z >> R) so that R can be ignored in Eq. 2. Then straightforward
differentiation gives the magnitude of the gradient as
|dB| 6 Bo
---- = --------- . 3)
|dz| z^4
This equation can be inverted and solved for Bo as a function of the
measured gradient:
z^4 |dB|
Bo = ------ ---- . 4)
6 |dz|
When J was on the far side of the pond he was about 18 m from the
trees. The measured gradient when J pointed the gradiometer toward the
treetops was about 18,000 nT/m. If we assume that the source was a current
loop at the distance of the trees with its axis pointing toward J when he
stood on the far side of the pond, then the measured gradient multiplied by
z^4 and divided by 6 gives Bo = 0.31 T - m^3. Using the definition Bo = 1E-
7IS, the equivalent current dipole source is found to be IS = 3.1E6 amp -
m^2. With this dipole strength we can use Eq. 2 to calculate the field at
the center of a loop. Assume that the loop has a radius of 0.5 m. Then, at
z = 0, B = 2 x 0.31/0.5^3 = 5 T. A field this strong is comparable to
saturation field strengths inside the strongest magnets.
When J stood under the trees he obtained a frequency that corresponds
to about 25,000 nT/m. Assuming that the source was at the treetops or just
above, at a distance of 3 m, Eq. 4 yields Bo = 3.5E-4 T - m3, which is much
lower than the previously calculated value. This large decrease results
from the assumption of a short distance (3 m vs 18 m) combined with the
fourth power distance dependence of the gradient. In this case the current
loop strength is 3.4E3 amp - m2 which is still quite large.
If one makes the reasonable assumption that the source strength should
have been the same for both measurements then one must abandon the
assumption that the source was above the trees. Using Eq. 4 with the two
values of |dB/dz| to calculate the ratio of the z distances we find
(z2/z1) = (dB1/dB2)^1/4 where z1 is the distance from the first measurement
location and z2 is from the second (trees). The ratio is
(18,000/25,000)^1/4 = 0.92 which means that the source would have been about
equidistant between the measurement locations (z2 = 0.9 z1) and hence at
some height above the pond. Alternatively the source had a complicated field
configuration which gave rise to the measured gradients.
The text makes a passing mention of the possibility that monopoles
might be involved. It is amusing to calculate the source strength if the
source were actually monopolar (a collection of monopoles) with magnetic
charge Qm. In this case it makes no sense to compare the strength to a
current dipole (a loop of wire carrying a current, as above). The field at
distance r from the center of the monopolar source is B = Bo/r^2, where Bo
is T - m^2. Therefore the magnitude of the gradient is |dB/dr| = 2Bo/r^3 so
Bo = r^3|dB/dr|/2. This is the monopolar analogue of the dipolar Eq. 4,
above. From this equation we can calculate Bo for r = 18 m and |dB/dr| =
18,000 nT/m: Bo = 0.05 T-m^2. Similarly for r = 3 m and |dB/dr| = 25,000
nT/m, Bo = 0.0003 T-m^2. The latter two calculations assume the source was
over the trees and yield different values of Bo. The same Bo value can be
obtained for both calculations if the assumed radial distances are adjusted
appropriately, as was done above for the dipolar source: r1^3|dB1/dr| =
r2^3|dB2/dr| or r2/r1 = (dB1/dB2)^1/3 = 0.9 where r1 is the distance from
across the pond and r2 is the distance from the trees. This calculation
says that the assumed monopolar source would have been at some altitude and
almost halfway between the two measurements locations (r2 = 0.9 r1).
The implications of these calculations are discussed in the text.
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* This paper was first presented at the Washington, D.C. Annual Meeting
of the American Physical Society in April, 1993
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Illinois (1975), pp. 86-87
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Scott, W., The Physics of Electricity and Magnetism, Wiley and Sons, New
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