Electric Comets
“Comets are perhaps at once the most spectacular and the least well understood members of the solar system.”
–Marcia Neugebauer, JPL
At the end of the nineteenth century neither an electric Sun hypothesis nor a theory of electric comets would have been controversial. Both were discussed in scientific papers. Around the same time, Kristian Birkeland performed his electrical Terrella experiments, reproducing the behavior of sunspots and auroras.91
Then science took a wrong turn. Investment in a theory began to override critical attention to observation and to experimental testing of alternatives. Astronomers shunned Birkeland, whose work posed new and promising possibilities. Not until the latter half of the 20th century did innovative scientists again consider electrical explanations, con- centrating their investigations in the fields of electrical engineering and plasma science, rather than astrophysics. Alfvén devoted chapters in his 1981 book Cosmic Plasma,92 to the electric circuits of the Sun, planets, and comets. But still, few astrophysicists were listening.
Each time a comet is observed close up, we are told that our understanding of comets and the origin of the solar system will be revolutionized. But the revolution never happens. The established story about comets has become an article of faith.
The French artist Georges Braque suggested that it is always useful to have two ideas, one to challenge or dispose of the other. Astronomers have only a single idea about comets, and the lack of competition encourages behavior that is more interpretive than investigative. In the absence of skepticism, intellectual curiosity gives way to conformity and conceit, as when NASA inscribed the words of Fred Whipple, the originator of the ‘dirty snowball’ comet model, on a microchip carried by the Stardust spacecraft in 2004: “Today we know that comets are black and cold, consisting of ices and dust that coalesced from an interstellar cloud as it collapsed to form the solar system.” We know no such thing.
We have never observed an interstellar cloud collapsing to form a planetary system. And no gravitational accretion model has been able to explain the weird assortment of solar planets. Dusty rings and disks around stars have been discovered, but it is pure conjecture to call
In 1950, Fred Whipple proposed a model of comets that became famously known as the “dirty snowball” hypothesis.
Photo Smithsonian Astrophysical Observatory, courtesy Dr. Whipple
91 K. R. Birkeland, The Norwegian Aurora Polaris Expedition, 1902-1903, Volume 1: On the Cause of Magnetic Storms and The Origin of Terrestrial Magnetism. Published 1908.
92 H. Alfvén, Cosmic Plasma, Astrophysics and Space Library, Vol. 82, D. Reidel Pub- lishing Co. 1981.
Of all the bodies in the heavens, perhaps none will prove more definitive in confirming the electric field of the Sun than the comet.
Image Credit: NASA
them ‘gravitational accretion’ disks, since we also observe those stars
ejecting matter in defiance of gravity.
If comets are dirty, icy leftovers from the primordial formation of the planets, why are the nuclei so black? Why does comet dust show minerals expected to have formed at high temperatures near the Sun? How does a tiny comet nucleus produce a finely filamented plasma tail that stretches for tens of millions of kilometers across the solar system? If the tail is formed of matter evaporated from the comet by the Sun’s heat, why is the matter ejected in energetic jets? And why do comet nuclei present us with such sharply carved relief, when the surface was supposed to look like a softened ice cream melting in the Sun? The questions are legion, while the ‘explanations’ invariably come after the fact and as disconnected guesses. Yet seldom is the popular myth of comet origins questioned.
By all appearances comet nuclei appear to be complex, cratered rocks a few kilometers in diameter. All that seems to distinguish them from those other space mountains—asteroids—is their eccentric orbits and accompanying displays in the heavens. Indeed, we now know that some asteroids occasionally exhibit cometary comas. One schizoid object, Chiron, is classified a ‘Centaur,’ named after a mythological figure that was half man, half horse. This, of course, refers to the ‘half and half’ (comet/asteroid) nature of Chiron. Yet rocky asteroids were thought to be much more evolved bodies than comets, and no one had imagined that the distinction between comets and asteroids would break down as it has in recent years.
Space age attempts to determine the composition and structure of comets have, in fact, left Whipple’s dirty snowball model in disarray. Infrared spectra of several comets have shown the presence of the mineral olivine, which requires a temperature of between 1,100 and 1,600 Kelvin and the absence of water, to form crystals. Such a temperature would have driven off any ices. So an ad hoc requirement was added—that the ‘hot’ and ‘cold’ components of a comet must be formed in separate regions of the primordial nebula and then later mixed together. Ironically, a similar problem of mixing high and low temperature components is found in meteorites, and in this case a few adventurous astronomers have attributed the enigmatic composition to the effects of lightning in the early solar nebula—an explanation at least pointing in the right direction.
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Early Electric Theories of Comets
Professor W. Stanley Jevons wrote in Nature, December 28, 1871:
“The observed regular diminution of period of Encke’s comet is still, I believe, an unexplained phe- nomenon for which it is necessary to invent a special hypothesis, a Deus ex machina, in the shape of an imaginary resisting medium... It is asserted by Mr. R.
- Proctor, Osborne Reynolds, and possibly others, that comets owe many of their peculiar phe- nomena to electric action... I merely point out that if the approach of a comet to the sun causes the devel- opment of electricity arising from the comet’s motion, a certain resistance is at once accounted for.”
In July 1872, Scientific American informed its readers that “Professor Zollner of Leipsic” ascribes the “self-luminosity” of comets to “electrical excite- ment.” According to the article, Zollner suggests that “the nuclei of comets, as masses, are subject to gravitation, while the vapors developed from them,
which consist of very small particles, yield to the ac- tion of the free electricity of the sun....” Also the August 1882 English Mechanic and World of Science wrote of comet tails: “...There seems to be a rapidly growing feeling amongst physicists that both the self- light of comets and the phenomena of their tails be- long to the order of electrical phenomena.” Similar ideas about comet’s tails appear in Nature, Jan 30, 1896: “It has long been imagined that the phenome- non of comet’s tails are in some way due to a solar electrical repulsion, and additional light is thrown on this subject by recent physical researches.”
In 1924 Hugo Benioff published The Present State of the Electrical Theory of Comet Forms.
Benioff noted that electrostatic repulsion of ionized
comet tails required “a value of the solar charge which is over one hundred times larger than can be accounted for by any known ways of producing such a charge.”
The solar charge was positive and estimated to be 127 times greater than could be achieved by the escape of electrons from a hot Sun. Benioff con- cludes that “It would seem best therefore to attribute the Sun’s repulsive action on the tail particles to ra- diation pressure rather than to electrical action since the former has been shown to be adequate to account for the facts qualitatively at least.”
However, there is a vast gulf between what may work for a single phenomenon qualitatively and what must work for all phenomena quantitatively. Here we see how critical it is to choose the correct model be- fore applying any mathematical analysis. When working with incorrect assumptions, mathematics merely “allows one to be wrong with confidence.”
Benioff admits “There are other phenomena associated with comets that indicate the presence of electrical forces. The outward radial motions in all directions of particles close to the nucleus are best explained as resulting from an electrical charge as- sociated with the nucleus.” But once again, the model proposed for charging the comet nucleus is naïve and merely considers charging by photo-ionization. Sci- ence is supposed to advance by revisiting earlier as- sumptions in the light of new knowledge.
Clearly, that has not happened.
INFORMATION PANEL
On its journey through the inner solar system, Comet Hale-Bopp began discharging out past the orbit of Jupiter—too far from the Sun for a “snowball” to melt. Four years after Hale-Bopp left the inner solar system, it was still active. It displayed a coma, a fan-shaped dust tail, and an ion tail— even though it was farther from the Sun than Jupiter, Saturn or even Uranus. Credit: N. Thomas (MPAE) et al.,
1.5-m La Silla Telescope, ESO
Jan Oort (1900-1992)
Courtesy: Leiden University
Astronomers continue to attribute a comet’s star-like nucleus and gigantic glowing coma and filamentary tail to solar heating as it nears the Sun. But as far back as 1991, it was already apparent that something was wrong with such a simple solar heating model. Moving between the orbits of Saturn and Uranus—a distance fourteen times farther from the Sun than the Earth—Comet Halley inexplicably flared up. At that distance solar heat does not sublimate ices. But telescopes showed that the 15-kilometer nucleus had ejected a cloud of dust that stretched more than 300,000 kilometers. But under the inertia of official theory, such surprises are invariably minimized and quickly forgotten.
Repeatedly, astronomers have observed comets ejecting material in narrow jets of gas and very fine dust. Hale-Bopp emitted more dust than could be explained by subliming ices. Observations of comet jets by earth-based instruments and space probes since 1985 have revealed distinctive similarities to the discharge plumes from Jupiter’s moon, Io—though no astronomer is about to call Io a comet. And the surface of comet Tempel 1, viewed in one of our closest-ever looks at a comet nucleus, showed the same similarities to electric discharge machining (EDM) features that the Galileo probe revealed on the surface of Io.
The violent jets seen exploding from Comet Halley in 1985, like those of Comet Borrelly in 2001, were far more energetic than could be explained by sublimation of ice in the heat of the Sun. And close-up views showed that it is not the full sunward faces of cometary nuclei but well-focused discharge jets, some on the dark side, that produce the spectacular tails of comets.
The Origin of Comets
Because comets lose considerable material at each pass around the Sun, the ones we see cannot have been around for long. Of course more than one answer to this dilemma might have been proposed, but astronomers chose one theory in particular, and it has posed dilemmas ever since. They claimed that since the formation of the planets billions of years ago, comets have occupied the deep freeze beyond the solar system. There they form an invisible cloud of icy objects located about 1000 times farther from the Sun than Pluto, a good fraction of the way to the nearest star.
The imagined cloud is named after Jan Oort, the astronomer who proposed the idea. After billions of years, somehow a comet is deflected from the Oort cloud into the inner solar system. The disturbance is surmised to be due to a passing star or the movement of the Sun above and below the galactic plane. But many astronomers have pointed to the lack of evidence for sporadic comet showers that such disturbances should unleash, and they have concluded that such
events, if they do occur, could only account for about one-fifth of the comets we see.
Astronomer Tom Van Flandern has devised a scale model that demonstrates the implausibility of the Oort cloud theory.93 If the Earth’s orbit were represented by the period at the end of this sentence and Pluto’s orbit by a circle of one-centimeter diameter, then the nearest star is 41 meters away. The Oort cloud of comets would orbit near a sphere 6 meters in diameter containing one comet per cubic millimeter. The comets would move at about 3 millimeters per 1000 years. Within this scheme they are effectively motionless with respect to the Sun. Passing stars on rare occasions will sail past at a meter per 1000 years and stir up the nearby comets. Less than 1 in 10,000 disturbed comets will be knocked onto a path that will target the 1-millimeter or so sphere surrounding the Sun where a comet might be seen from the Earth.
Having visualized this, Van Flandern makes the point that the true size of a sphere encompassing Pluto’s orbit is so vast that all of the 200 billion stars in our galaxy would fit with room to spare in that volume. He writes, “But the volume enclosed by the comet cloud is a billion times greater yet. It truly is unimaginably large, surviving as a plausible idea in large part because our intuitions fail so miserably to comprehend the vastness of this volume.”
But the imagined Oort cloud is needed to save a cosmological theory. And even so, it leaves vast discrepancies between the theory and things that are observed. The model itself implies that a significant percentage of comets will be on ‘hyperbolic’ orbits and launched out of the solar system by the Sun’s gravity. But this is not observed.
Conversely, the observed number of short-period comets (with periods of revolution less than 200 years) is two orders of magnitude more than the Oort cloud model would predict.
Comet Theory in Crisis
Scientists at the end of the nineteenth century could see the many parallels between the behavior of a luminous comet and a laboratory glow discharge (see information panel p. 87). It was even acknowledged that the acceleration of the comet tail away from the Sun requires an electrified Sun. But in the following decades that vision was abandoned. What happened to allow this promising idea to founder, to be replaced with an inert mechanical model of a comet?
The answer seems clear—an understanding of the plasma environment in space was lacking at that time. Irving Langmuir did not coin the word ‘plasma’ until 1927. So early electrical theories of
Diagram on a logarithmic scale showing the relationship between the imagined Oort cloud of comets and the solar system.
93 T. Van Flandern, Dark Matter, Missing Planets & New Comets, pp. 180-1.
The nucleus of comet Halley as seen by the Giotto space probe. Credit: ESA/MPAE
comets were based on unworkable electrostatic arguments. The idea of electricity in space quickly became anathema to astronomers.
With the space age discovery of the solar ‘wind’ of charged particles, however, astrophysicists would have been wise to revisit the physics of gas discharges. Instead, they switched from the 19th century view of space as a perfectly insulating vacuum to the polar opposite, where space plasma was treated as a perfect conductor, trapping magnetic fields and preventing voltage differences between bodies in space. This turn, according to Alfvén, amounted to ‘pseudo-science’ and would lead to a crisis in astrophysics.94 That alarm was raised more than 3 decades ago. It has been ignored to this day and the crisis is now upon us.
Under the spell of theoretical assumptions, and lacking the training to recognize electrical discharge phenomena in space, astrophysicists explain comet behavior in terms of electrically neutral ‘magnetohydrodynamics.’ In other words, ‘winds’ and ‘supersonic shocks’ in electrically conducting, magnetized gas. They have ignored Alfvén’s warning that magnetic fields cannot be ‘frozen in’ to the diffuse plasma of the solar wind and the comet’s coma and tail. They are unaware that a source of electrical energy is required to produce and sustain cometary phenomena.
Consequently, the electric discharge model was not even on the table at the beginning of the space age, allowing astronomers to embrace Whipple’s dirty snowball model as the scientific consensus. An endless series of surprises followed, as when cometologists caught their first close-up look at Halley (left): “a surprising result of the Giotto and Vega spacecraft encounters with Comet Halley in March 1986 was the discovery of a shell-like region of high plasma density...” But Alfvén wasn’t surprised. He had earlier written, “It is legitimate to conclude that space in general has a ‘cellular structure,’ although this is almost impossible to observe unless a spacecraft penetrates the ‘cell walls’ (current sheets).”95 In the approach to Halley, the spacecraft had penetrated the comet’s plasma cell wall, encountering a region whose stability and longevity could not be explained in terms of simple out-gassing from the comet.
Now, after four close flybys by spacecraft and one impact event, comets are more of an enigma than ever for astronomers. On July 4, 2005, the world watched NASA astronomers on television gleefully celebrating the Deep Impact mission’s direct hit on comet Tempel 1. But later, when the cameras had gone, the astronomers were left scratching their heads in confusion. The Deep Impact team had hoped that the impactor would kick up a relatively small cloud of dust from
94 H. Alfvén, “Plasma physics, space research and the origin of the solar system,”
Nobel Lecture, December 11, 1970, p. 308.
95 H. Alfvén, Space Plasma, 1981, p. 40.
Tempel 1, dig a crater, and expose pristine icy material underneath. There was even some doubt amongst the Deep Impact team whether the spacecraft cameras would see any effect at all. Instead there was a puzzling initial flash followed by an incredible outburst of dust as fine as talcum powder—an effect that left every observer stunned.
The New Scientist reported, “We have now had four close encounters with comets, and every one of them has thrown astronomers onto their back foot.”96 The popular model of comets as dirty snowballs no longer fits space age discoveries.
When a theory fails to anticipate discoveries and theorists are continually surprised by new data, it is essential that the theory be questioned. Astronomers believe that by discrediting a simplistic early electrical model of comets they had dismissed all electrical models. Is this stance justified in the light of what we now know about plasma discharge phenomena? The question can be answered by comparing the dirty snowball model with a new plasma discharge model of comets.
In the accepted model, a comet is an aggregate of ice and dust evaporating in the heat of the Sun. In the electric model, a comet could be a solid rock discharging as it plunges more deeply into the Sun's electric field. A proper comparison of the two models, however, will require attention to details, accentuating the contrast between two radically different perspectives. Systematic comparison can only highlight the contrasts in predictive ability—the test of a good theory.
Dirty Snowball Model
- The solar system formed billions of years ago by gravitational accretion from a primordial solar nebula, which formed a disk of in- terstellar dust and
- Gentle or ‘sticky’ collisions agglomerated the dust and ices into larger bodies (planetesimals).
- In ways not understood, the planets then grew by ‘runaway ac- cretion’ of
- The leftover dust and gas was dispersed by a presumed energetic phase of the early
- The planets found themselves in remarkably circular
- Comets are supposed to be composed of undifferentiated ‘proto- planetary debris’—dust and ices left over from the formation of the outer planets where temperatures in the disk were On this model, comets are a mixture of frozen water, carbon monoxide, methane, ammonia and about an equal amount of dust.
- Comets are injected into the inner and outer solar system from a vast unseen reservoir called the ‘Oort ’ Those in the inner solar
96 S. Clark, “Comet tails of the unexpected,” New Scientist, 9 September 2005.
system contributed to an early episode of heavy bombardment of the inner planets. Those flung outward were lost or somehow ‘stored’ in the Oort cloud, to be occasionally disturbed back into the inner solar system by a passing star.
- Comets in the Oort cloud are exposed to radiation, or space weathering, for billions of Only the upper surface layers are affected.
- As the comet swings through the inner solar system, radiant heat from the Sun sublimates ices from the nucleus. The gases and ac- companying dust expand around the nucleus to generate the coma and are swept back by the solar wind to form the comet’s ion and dust
- Repeated passages around the Sun vaporize surface ice and leave a ‘rind’ of
- Pockets of gas form where solar heat penetrates the surface of the blackened, shallow crust. Energetic jets form where the gas breaks through the
- The comet coma is generated by the collision of gases from the comet with the solar Comet comas are amongst the largest ob- jects in the solar system.
- Strange accelerations of comets are due to ‘rocket action’ of the jets from the
- Comets disintegrate because pockets of gas form inside the nu- cleus, solar heating increases the pressure, and the fragile nucleus fractures.
Plasma Discharge Model
- The plasma discharge model of comets is inseparable from the electric Sun This model envisions the Sun forming in a galac- tic electromagnetic ‘Z-pinch’ at some unknown time in the past. A Z- pinch is the most effective long-range scavenger of interstellar dust to form stars. Laboratory experiments show that a number of ‘stars’ are formed simultaneously along the axis of a Z-pinch. Once the ‘pinch’ subsides the stars ‘scatter like buckshot.’
- Planets are formed in several separate episodes of ‘electrical parturition’ of stars and gas giants. Stellar ‘accretion disks’ and planetary rings are in fact ‘expulsion ’ This model accounts for ‘hot Jupiters’ found closely orbiting their parent star. Stellar ejection of ‘blobs’ of matter is observed in deep space. The rings of our gas giants are evidence of past electrical expulsions.
- Subsequent electromagnetic capture and circularization of planetary orbits is accompanied by interplanetary plasma
- Moons, comets, asteroids, meteorites and planetary rings are debris that has been electrically expelled or torn from a planetary Their composition will vary depending on the parent body.
- Comets were electrically ‘machined’ in their natal event. Blackened and pitted comet surfaces reflect their origin in an intense plasma Comets can be considered ‘asteroids on eccentric orbits.’
- Comets follow elongated paths within a weak radial electric field centered on the Sun. All solar system bodies, including comets, are negatively charged with respect to the Sun. Comets spend most of their time remote from the Sun, and while there, they adopt a voltage in keeping with that environment.
- As a comet accelerates toward the Sun, it en- counters a steadily rising plasma density and volt- age. The strength of the electric field within the
comet’s plasma sheath thus steadily increases until the plasma dis- charge suddenly switches from dark mode to glow mode (see infor- mation panel p. 96).
- A glow discharge produces the visible coma around the
- Eventually, increasing electrical stress on the nucleus causes the discharge to switch suddenly to ‘arc’ mode. Cathode arcs begin to dance over the comet nucleus, giving it a star-like appearance through a
- Rock is electrically ‘sputtered,’ particle by particle, from the surface and accelerated vertically into space in the form of well- collimated jets, following the natural curved trajectories of particles from a ‘plasma ’
- The ejected ionized material is guided electromagnetically into a coherent comet tail. The ion tails of comets reveal well-defined Birkeland current filaments extending up to tens of millions of km without dissipating in the vacuum of space—a ‘violation’ of gas behavior in a vacuum. (Heated gas in a vacuum will normally disperse )
- Puzzling comet behavior becomes a unified and predictable result of plasma discharge The cathode-arc discharges to the nucleus produce the characteristic forms of electric discharge machining (EDM) of the comet surface, with sharply scalloped craters, terraces and mesas.
- Cathode arcs tend to jump from one spot to another, which explains the sudden switching off and on of comet
- The wandering cathode arcs, seen as enigmatic white spots in close-up images of the comet nucleus, erode the surface and burn it black, which accounts for the surprising discovery that comet nuclei are the darkest bodies in the solar system, “blacker than copier ”
Comet West in its most dramatic display in March, 1976. The colossal size of cometary displays cannot be explained by the passage of a tiny body through an extremely tenuous solar ‘wind’ and relying on solar heating alone to remove material from the nucleus.
Credit: Observatoire de Haute, Provence, France
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‘Deep Impact’—Where is the Water?
Deep Impact saw absolutely no evidence for any ice on the surface of comet Tempel 1. At 56 ˚C (133 ˚F) on the sunlit side it was too hot for ices. However, it was reported that there's plenty of ice visible in Tempel 1's coma.
On viewing comet comas spectroscopically and observing the hydroxyl radical (OH), astronomers simply assume it to be a residue of water ice (H2O) broken down by the ultraviolet light of the Sun (photolysis). This assumption requires a reaction rate due to solar UV radiation beyond anything that can be demonstrated experimentally.
A report in Nature more than 25 years ago cast doubt on this mechanism. As
Comet Tago-Sato-Kosaka
moved away from the Sun, OH production fell twice as fast as that of H, and the ra- tio of OH:H production was lower than expected if H2O was dominant. The report concludes, “cometary scien- tists need to consider more carefully whether H2O-ice really does constitute a ma- jor fraction of comet nu- clei.”
The mystery of ‘missing water’ is resolved electri- cally in the transaction be-
tween a negatively charged comet and the Sun. In this model, electrical discharges strip negative oxy- gen ions from rocky minerals on the nucleus and accelerate the particles away from the comet in en- ergetic jets. The negative ions then combine with protons from the solar wind to form the observed OH radical, neutral H2O and H2O+.
Alfvén and Gustav Arrhenius note, “The as- sumption of ices as important bonding materials in cometary nuclei rests in almost all cases on indirect evidence, specifically the observation of atomic hy- drogen and hydroxyl radical in a vast cloud sur- rounding the comet, in some cases accompanied by observation of H20+ or neutral water molecules.”*
INFORMATION PANEL
The abundance of silicates on comet nuclei, confirmed by infrared spectrometry, led the authors to cite experiments by Arrhenius and Andersen. By irradiating the common mineral, calcium alumino- silicate (anorthite), with protons in the 10 kilovolt range, the experiments “resulted in a substantial (~10 percent) yield of hydroxyl ion and also hy- droxyl ion complexes [such as CaOH.]”
A good reason for the experiments was al- ready in hand. Observations on the lunar surface reported by Hapke et al., and independently by Ep- stein and Taylor had “already demonstrated that such proton-assisted abstraction of oxygen (prefer-
entially 016) from silicates is an active process in space, resulting in a flux of OH and related species.”
The authors note in addition that this removal of oxygen from particles of dust in the cometary coma could be much more efficient than on a solid surface with limited exposure to available pro- tons: “The production of hydroxyl radicals and ions would in this case not be rate-limited by surface satu- ration to the same extent as on the Moon.”
The authors conclude: “These observations, although not negating the possible occurrence of water ice in cometary nuclei, point also to refrac- tory sources of the actually observed hydrogen and hydroxyl.” Additionally, they note, solar protons as well as the products of their reaction with silicate oxygen would interact with any solid carbon and nitrogen compounds characteristic of carbonaceous chondrites to yield the volatile carbon and nitrogen radicals observed in comet comas.
*H Alfvén and Gustav Arrhenius, Evolution of the Solar System, NASA SP-345, 1976, p. 235.
- Ices are not buried beneath a dirty crust. The presence of water is inferred from the hydroxyl molecule [OH] in the comet’s coma. New evidence shows that the main source of OH is the combination of hydrogen from the solar wind with negative oxygen ions, sputtered from cometary surface minerals (see information panel on facing page). 97
- Electrical heating of the surface of the comet nucleus and the lack of cooling effect from non-existent sublimating ices ac- counts for the higher than expected temperatures of the comet nucleus (see right).
- The diameter of the visible coma will often reach several millions of It is the electric force, not gravity, that enables the cometary nucleus to hold the coma in place as it careens around the Sun.
- It is the electric force that accelerates the ion tails of a comet as it sweeps around the
- The coma temperature (as hot as the solar corona) and the emission of X-rays are both explained as plasma discharge phenomena.
- Comet nuclei behave like an electret (similar to a capacitor, but able to store electric charge for a much longer time). As such the nucleus can explode when the internal electrical stresses, caused by the discharge activity at the surface, results in an internal The many examples of an exploding comet are thus analogous to an exploding capacitor, in which the insulating dielectric suffers a spark-over and fails. The current through the dielectric causes sudden internal heating, which may explosively fragment the capacitor.
Comets, Electricity and Gravity
Astronomers have calculated the mass and density of comet nuclei from their presumed gravitational effects on the trajectories of nearby spacecraft. By this reasoning, comet Halley had a density of only one tenth to one quarter that of water. But seen in close-up, all comet nu- clei look like solid rock. What is going on?
Science surprisingly takes no account of the electrical nature of matter when it comes to the related phenomena of inertial mass and gravity. It is a crucial factor here. Though we intend to take up the issue of the ‘gravitational constant’ in a forthcoming monograph, it is proposed that, if gravity is due to an extremely weak electric polarization of subatomic particles within charged bodies, gravitational
Comet Borrelly's nucleus, as recorded by Deep Space 1 on September 22, 2001. Borrelly's ‘icy heart’ exhibits no trace of water ice or any water-bearing minerals. Moreover, the nucleus is actually quite hot — ranging from 300 to 345 Kelvin (80° to 160° F).
Credit: NASA/JPL.
97 L. Kristoferson, K. Fredga, “Laboratory Simulation of Cometary Erosion by Space Plasma,” Astrophysics & Space Science 50 (1977) pp. 105-123. “the production of OH in space from ’dry,’ water free matter is possible by means of molecular sputtering from several cosmically abundant types of materials.” However, the production rate is too low without electrical sputtering.
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determination of the masses and densities of celestial bodies are immediately suspect.98
We have suggested that the nucleus of a comet can be con- sidered an electret. An electret is a permanently electrified sub- stance. If it is separated into pieces, each piece will be electrified. Due to its small size, the effect of charge polarization within an electrified comet will be small. We might expect, therefore, that its gravitationally measured mass will be lower than expected for the same rocky mass if it were on the Earth’s surface. In other words, if comets look like solid rock they probably are solid rock. If this model is correct, simple Newtonian calculations of density and composition that assume G is a universal constant will be misleading.
Evidence for electrical stress in comets comes from their propensity for energetic disintegration, often at large distances from the Sun where solar heating is minimal. Just as electrical breakdown of the dielectric material causes a capacitor to explode, electrical discharges from a comet surface can induce large electric fields within the subsurface rock, leading to breakdown and explosive fragmentation of the comet nucleus.
In addition, most large comet nuclei do not exceed one billionth of the mass of the Earth. How can a piece of rock, no more than a few km wide, gravitationally hold a ten-million-kilometer-wide bubble against the force of the solar wind? The entrained envelope is extremely diffuse, but in gravitational terms it should not be there.
Something stronger than gravity is at work here. If a comet holds a large negative charge, it will give rise to an immense Langmuir plasma sheath. This vast envelope is formed and held electrically. A gravitationally trivial object can be very powerful electrically.
The frequent erratic motions of comets must also be explained. To account for such motions, which are dubbed ‘non-gravitational,’ Whipple looked to the ‘jets’ seen erupting from the nucleus. As summarized by Francis Reddy in an obituary the day after Whipple’s death in 2004, the astronomer believed that, “The jets supply a force that can either speed or slow a comet, depending on the way it rotates
—a force unaccounted for in the astronomical calculations used in predicting comet returns.”99 So as comet Linear moved toward perihelion, a NASA release stated, “Powerful jets of gas vaporized by
98 Astrophysicists as a whole have never considered that, if gravity is a dipolar elec- tric force between distorted subatomic particles, similar to the ‘London force’ between electrically neutral molecules, then the universal ‘constant’ of gravitation, G, is actually a variable, dependent on the electrified state of the body. This disturbing idea is sup- ported not just by the electrical behavior of comets, but by the fact that G on Earth is the most elusive physical ‘constant’ in physics.
99 www.astronomy.com/asy/default.aspx?c=a&id=2429
When comet Linear blew apart in the summer of 2000, the event high- lighted the failure of popular comet theory to anticipate the actual attrib- utes and behavior of comets. Linear was not the ‘dirty snowball’ of modern comet lore, and its remains included little if any water at all.
Credit: NASA, Harold Weaver (the Johns Hopkins University), and the HST Comet LINEAR Investigation Team
The Hubble Space Telescope captured this image of a flare emerging from comet Tempel 1 on June 14.
Such dusty outbursts are only one of many features of comets that astronomers “don’t fully understand.” Credit: NASA/HST
Comet Material Born in Fire
The image on the right shows a comet particle collected by the Stardust spacecraft. The particle is made up of the sili- cate mineral forsterite, also known as peridot in its gem form. It is surrounded by a thin rim of melted aerogel, the substance used to collect the comet dust samples. The particle is about 2 micrometers across.
NASA’s celebrated Stardust mission returned to Earth the first samples ever of comet dust. On Janu- ary 2, 2004, the Stardust craft swept past Comet Wild 2, trapping particles as they struck ‘aerogel’ in a 100- pound capsule. The capsule parachuted to a Utah desert on January 15, 2006.
Shockingly, the particles contained minerals that can only be formed at temperatures of thousands of degrees. Mineral inclusions ranged from anorthite, which is made up of calcium, sodium, aluminum and silicate, to diopside, made of calcium magnesium and silicate.
How could this be? We have been assured that comets are the leftovers of a cold ‘nebular cloud’ that formed the solar system. This hypothesis has become an article of faith. Indeed, the implication of a fiery cometary past was so unexpected that an early sample of dust was thought to be contamination from the spacecraft.
“How did materials formed by fire end up on the outermost reaches of the solar system, where tem- peratures are the coldest?” asked Associated Press writer Pam Easton.
“That’s a big surprise. People thought comets would just be cold stuff that formed out ... where things are very cold,” said NASA curator Michael Zolensky. “It was kind of a shock to not just find one but several of these, which implies they are pretty common in the comet.”
Researchers were forced to conclude that the en- igmatic particle material formed in a superheated re- gion either close to our Sun, or close to an alien star. “In the coldest part of the solar system we’ve found samples that formed at extremely high tempera- tures,” said Donald Brownlee, Stardust’s principal investigator at the University of Washington in Seat- tle. “When these minerals formed they were either
red hot or white hot grains, and yet they were col- lected in a comet, the Siberia of the Solar System.” But comets are supposed to be the ‘Rosetta stones,’ constituted primarily of dust and ices, from
which the Sun and planets were formed.
Speculations erupted. Could it be that something occurred in or very near the Sun in its formative phase, flinging immense quantities of material out far beyond the orbit of Pluto, to the ‘Oort cloud,’ the legendary and invisible reservoir of comets? But this would produce a mixing and contradict the zoning that is evident in the asteroid belt. “If this mixing is occurring, as suggested by these results, then how do you preserve any kind of zoning in the solar system,” Zolenksy asked. “It raises more mysteries.”
Perhaps the story could be rescued by finding the signature of primordial water whose existence is es- sential to the survival of official comet theory.
A report in the journal Nature is illuminating. Phil Bland, a planetary scientist at Imperial College Lon- don and his team analyzed part of a grain. When he found large amounts of calcium, Bland was excited. Could the calcium be present in the form of calcium carbonate, a mineral that almost always forms in wa- ter? He bet his colleague Matt Genge that this would indeed be the case.
Bland lost the bet. According to the Nature report NASA “scientists have not yet found any carbonates in their grains.”
(See, also, information panel p. 94.)
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INFORMATION PANEL
solar radiation have been pushing the comet to and fro.”100
Astronomers applied the same interpretation to the energetic jets of Borrelly and Wild 2 (pronounced ‘Vilt 2’). But in the case of Wild 2, the close-up photographs gave no indication of caverns shaped into ‘jet venturis’ that could confine the jets to a narrow stream and produce the measured high jet velocities. And even with velocities up to 1 km/ sec (well above the 0.25 km/sec corresponding to ice subliming into a vacuum) the jets are too weak to influence the orbit of a comet the size of a small mountain. However, if the value of the gravitational ‘constant,’ G, is dependent upon the electrical polarization inside a comet, strong electrical discharging will change that value. And changes in G between the Sun and a comet will directly affect the comet’s orbit.
Unexplained Surface Features
When the roughly 5 kilometers-wide Comet Wild 2 was first seen in dramatic close-up, Donald Brownlee, Stardust Principal Investiga- tor, said, “We thought Comet Wild 2 would be like a dirty, black, fluffy snowball. Instead, it was mind-boggling to see the diverse landscape in the first pictures from Stardust, including spires, pits and cra- ters,”101 features that are more likely for a solid rock than a melting, icy pile of rubble (see image right and on p. 101). Among the surface anomalies are two depressions with flat floors and nearly vertical walls that resemble giant footprints. They aren’t structured like typical im- pact craters.
Regardless, a number of scientists declared that the craters were the result of impacts—the catch-all explanation for craters in the space age. But in the vast emptiness of the outer solar system, impacts are exceedingly unlikely, and with the low relative velocities there, it is inconceivable that a small body would have attracted end-to-end cratering.
Today, most astronomers distance themselves from the impact explanation of the Wild 2 surface. But that leaves the mystery of cra- ter formation unsolved. Some astronomers suggested that the craters are sinkholes, formed when surface material fell into cavities left by the sublimation of buried volatiles. But the smooth, flat floors of the craters belie such an explanation. Nor is it reasonable to suggest that heat from the Sun would reach down through many meters of insulat- ing material to remove subsurface volatiles in volumes sufficient to provoke surface collapse. And even if that were a plausible sequence, the miniscule gravity of comet nuclei is hardly sufficient to justify a comparison of their craters to terrestrial ‘sinkholes.’
100 science.nasa.gov/headlines/y2000/ast31jul_1m.htm
101 www.nasa.gov/vision/universe/solarsystem/stardust-061704.html
Credit: NASA/JPL-Caltech. ABOVE: A microscopic view of an EDM surface. Flat floored depressions with steep scalloped walls and terracing are evident. Image credit: B. Mainwaring
Comet Borrelly's nucleus, as recorded by Deep Space 1 on September 22, 2001. Details as small as 50 meters can be resolved on the 8-kilometer-long object. Image Courtesy NASA/JPL.
Dr. Earl Milton (1935-1999) was an associate professor of physics at the University of Lethbridge, Alberta, Canada. He was a close colleague of Ralph Juergens. He published sev- eral papers on the electric model of comets and other aspects of the elec- tric universe.
Photo: W. Thornhill, 1983.
Numerous strange pinnacles as long as 100 meters long jutting off the surface. The pinnacles were unex- pected. Other unusual Wild 2 sur- face features include long cliffs, deep pits and craters.
Credit: Stardust Team, JPL, NASA
A minority of astronomers came to suggest that some of the comet dilemmas could be resolved if comet nuclei were ‘rubble piles.’ But no comet, when seen close up, revealed surface features suggesting a heap of fragments. After the Deep Impact mission, NASA investiga- tors publicly stated that the rubble pile hypothesis had turned out to be a “non-starter.”
The images of comet nuclei from passing spacecraft support a complex history. The surface features of Comet Borrelly (right) were described as “Earth-like.” Dr. Dan Britt, a meteoriticist in the University of Tennessee’s Planetary Geosciences Institute, noted that the mesas on Borrelly resembled those in the American Southwest.
In a characteristic understatement, NASA scientists described the findings as “somewhat surprising.”
It is no overstatement to say that none of the defining features of comet nuclei has met the expectations of the Whipple model. In contrast their features are consistent with—and predictable—under the electric comet model.
Another pioneer of the electric universe, Earl Milton (top left), noted in 1980 that he and Juergens had independently concluded that a comet nucleus would be scarred “like an electrode in an arc. Over time the cometary nucleus should become cratered and pitted…When a spacecraft finally achieves a rendezvous with one of the comets, scientists are going to be surprised to find a surface pitted like that of the Moon, Mars, or Mercury.”102 At the time, scientists had never seen a comet surface. The first flyby of a comet took place 6 years later.
Other surface enigmas stand out as well. Images of Comet Wild 2 have revealed unexplained bright spots (below). In the electrical
model of comets, these are the ‘touchdown’ points of the cathode arcs—where electric currents between the comet and the Sun ‘pinch down’ on the more negatively charged nucleus of the comet. The result is analogous to electric discharge machining (EDM), etching the sur- face into the observed “spires, pits and craters.” They appear to be
102 E. R. Milton, “Glimpses of an Electrical Cosmos,” from a lecture given at San Jose in August 1980.
etched sharply into rock, offering nothing to support the idea of sublimating ice or snow (see right). The caption on the Astronomy Picture of the day lamely offers, “these fea- tures are hypothesized to be indicative of a very rigid sur- face sculpted by impacts and explosive sublimation. Ini- tially, Wild 2 was expected by many to be held together only quite loosely.”103
Generating Comet Jets
NASA’s Stardust spacecraft captured images of Comet Wild 2 on January 2, 2004. and issued a composite of the nucleus and a longer exposure highlighting the comet’s jets (facing page). According to a Stardust project press release, mission scientists expected “a dirty, black, fluffy snowball” with a couple of jets that would be “dispersed into a halo.”
Instead they found more than two dozen jets that
“remained intact—they did not disperse in the fashion of a gas in a vacuum.” The jets “...remained strong and coherent even hundreds of miles from the comet’s surface. Stardust’s very bumpy ride during its passage through the coma was an unmistakable sign of the power and strength of the jets.”104
Some of the jets emanated from the dark unheated side of the comet—an anomaly no one had expected. Chunks of the comet, in- cluding rocky particles as big as bullets, blasted the spacecraft as it crossed three jets. A principal investigator also spoke of energetic bursts “like a thunderbolt.”105
The extreme fineness, high speed and narrow trajectories of dust particles from comets has been a puzzle ever since the first flyby of Comet Halley by the Giotto spacecraft. But from an electric viewpoint these comet enigmas are easily explained: an arc impinging on a cathode or anode surface vaporizes and sputters matter from that surface; the electric field of the arc accelerates matter off the surface; an electromagnetic ‘pinch effect’ provides densities in the thin jets many orders of magnitude higher than those predicted from simple radial sublimation; and instabilities in the arc cause flickering and sudden relocation of jets in exceedingly short periods.
The jets are not due to solar heating but are generated by well- focused electric arcs wandering across the nucleus to progressively etch its surface, carving out the surface craters and flat floored valleys,
Comet Wild 2. This composite image uses a time exposure to reveal the jets. Credit: Stardust Team, JPL, NASA
103 See APOD website for June 22, 2004.
104 A. Alexander, “Pinnacles, Craters, and Multiple Jets: Early Results from Stardust Stun Researchers,” The Planetary Society, 17 June 2004.
105 “Comet’s Dust Clouds Hit NASA Spacecraft ‘Like Thunderbolt,” www.sciencedaily.com/releases/2004/06/040618070736.htm
and leaving spires and mesas, in the well-known process of cathode erosion.
Comets are, in fact, doing exactly what the electric model would predict. Given that out-gassing from an icy nucleus should vary in proportion to available surface area, it is suspicious that now five comets, adjusted to the same heliocentric distance, should have such similar rates of ‘loss of water’ (based on the presence of OH in the coma). But if material is being machined electrically from very small arc footprints, the surface area of the comet and solar heating are irrelevant to the volume of removed material.
Forming Comet Comas
The International Cometary Explorer (ICE) was the first spacecraft ever to pass through a comet’s coma boundary, which is misnamed a ‘bow shock.’ Before the encounter with Comet Giacobini- Zinner, astrophysicists were not sure whether a bow shock would be encountered at all: The boundary was called simply the ‘transition region.’
Without realizing it, the ICE mission confirmed the signature of electric current filaments in the plasma sheath. Electrical currents flow in the comet’s plasma sheath and cause atoms there to glow. The currents announced themselves by the magnetic turbulence present.
This was not the official interpretation, of course, but the observations conformed to Alfvén’s earlier electric circuit model of comets. He had written, “As Venus, like the comets, has no appreciable intrinsic magnetic field, the solar wind interaction with her is likely to be essentially the same.”106 A report in Science confirmed Alfvén’s prediction: “a similar field pattern [to the comet] has been observed at Venus.”107 Significantly, the magnetic field at the comet peaked at six times that found at Venus, revealing the degree to which a comet transacts electrically with the solar plasma.
Deep Space 1 provided further evidence of electrical effects as it flew through the plasmasphere surrounding the nucleus of comet Borrelly. Mission specialists had expected that the solar wind would flow symmetrically around the coma, with the nucleus in the centre. They found that the solar wind was indeed flowing symmetrically, but the nucleus was off to one side, shooting out a great jet of material. “The shock wave is in the wrong place,” said Dr. Marc Rayman. Dr. David Young of the University of Michigan added, “The formation of the coma is not the simple process we once thought it was. Most of the charged particles are formed to one side, which is not what we
106 H. Alfvén, Cosmic Plasma, Vol. 82, 1981, p. 60.
107 T. T. von Rosenvinge et al., “The International Cometary Explorer Mission to Comet Giacobini-Zinner,” Science, Vol. 232, 18 April 1986, p. 355.
expected at all.” One commentator said that it was like finding the shock wave from a supersonic jet a mile to the side of the aircraft!
However, the analogy is false. The luminous crescent in the image (right) is not due to the nucleus mechanically plowing through the plasma ahead of it. In a cometary plasma sheath, the most energetic recombination will take place under the direction of the electric force some distance from the comet nucleus in the di- rection of the Sun.
Direct confirmation of the electric nature of the coma came unexpectedly from the ROSAT satellite when it observed Comet Hyakutake in March 1996 (top right). “We had no clear expectation that comets shine in X-rays,” said Dr. Michael Mumma of NASA’s Goddard Space Flight Center. The X-rays were as
intense as those the satellite usually sees from bright X-ray stars. And the X-ray variability over a few hours was “remarkable.” The observation provoked scientists to say, “This important discovery shows that there must be previously unsuspected ‘high-energy’ processes taking place in the comet…”
On July 14, 2000, the Chandra telescope viewed the comet Linear repeatedly over a 2-hour period, detecting X-rays from oxygen and nitrogen ions (lower right). The observatory’s press release reports: “The details of the X-ray emission, as recorded on Chandra’s Advanced CCD Imaging Spectrometer, show that the X-rays are produced by collisions of ions racing away from the sun (solar wind) with gas in the comet. In the collision the solar ion captures an electron from a cometary atom into a high-energy state. The solar ion then kicks out an X-ray as the electron drops to a lower energy state.”108
The press release concludes that the Chandra observation “proves how comets produce X-rays.” Of course it doesn’t prove anything of the sort: in a process of circular reasoning that has become embarrassingly common in science, the model
provides the interpretation that is then claimed to prove the model. It is simply assumed that neutral gas from the comet supplies the electrons. However, that should produce a positively charged shell that would quickly repel further ions from the Sun. The alternative idea is not considered: that a comet is negatively charged and via the process of cathode sputtering supplies copious electrons and negative ions to the cometary electrical discharge. Negative cometary ions are a puzzle to astrophysicists because there is no way known of producing them to match the observed densities.109 It is now clear that these negative ions and electrons are jetted into the coma, where they combine with minor
Credit: C. Lisse, M. Mumma (NASA/GSFC), K. Dennerl, J.
Schmidt, and J. Englhauser (MPE)
As seen in this X-ray image of Comet Linear, the X-ray production occurred at the interface of the negatively charged cometary plasma with the positively charged particles of the solar wind. The excess of electrons in a cometary coma was first noted in 1986, when the Giotto spacecraft detected an abundance of negatively charged atoms in the inner coma of Comet Halley.
Credit:NASA/SAO/CXC/STScI/ Lisse et al.
108 chandra.harvard.edu/photo/2000/c1999s4/
109 J. Crovisier & T. Encrenaz, Comet Science, “These [negative] ions occurred with densities 100 times greater than expected, and the discrepancy with theoretical ac- counts is still not well understood.” p. 75.
ions in the solar wind, giving rise to the observed soft X- rays. The combination of electrons from the comet with ions from the solar wind is, of course, an electric discharge— Nature’s efficient means of X-ray production.
The gas ‘collision model’ is also refuted by the observed X- ray hot spots and rapid variability in intensity. Oscillatory and ‘bursty’ behavior is typical of plasma sheaths or double layers (see left).
Comet Halley in false color during a flare up. The jet extends 20,000 km to the lower left. The Sun is to the upper right. “The surprises included sudden outbursts in the presumably steady vaporization of its icy nucleus and a periodic, complex pulsation of the comet's brightness.” Flickers lasting only a few tens of seconds were recorded.
Credit: T. Rettig et al.,
See R. A. Kerr, Halley’s Confounding Fireworks, Science, Vol. 234, 5
December 1986, pp. 1196-8.
Comet NEAT and a solar CME. Credit: Solar and Heliospheric Observatory ESA/NASA (SOHO).