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Credit: Left, Halley Multicolour Camera Team, Giotto, ESA; Right, NASA/JPL


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May 23, 2005
Comets, Gravity, and Electricity

The study of comets in recent years has revealed many anomalies yet to be understood by comet observers. Most importantly, the new discoveries accent the inability of gravitational theory to account for the full range of comet behavior.

"Comets are perhaps at once the most spectacular and the least well understood members of the solar system."
M. Neugebauer, Jet Propulsion Laboratory

The more facts we gather about comets the less sense they make under popular scientific theories about comets.  Highly energetic and focused jets explode from comets’ nuclei and scar them with features similar to those on asteroids and satellites. The jets’ filamentary structures stretch across millions of miles. The apparent temperatures of comas are so high that x-rays and extreme ultraviolet light shine from them. Water and other volatiles are in short supply or are completely absent on the surfaces of many comet nuclei. Observed electrical transactions with the solar wind remain obscure to cometologists. And a perplexing number of comets mysteriously explode as they dart around the sun.

Though the popular theories have hardened into dogma and the scientific media present them as facts, the new discoveries challenge the popular assumptions. The metaphor of a “dirty snowball” does not fit what we know about comets in the space age. A vast library of data now contradicts the standard assumption of an electrically neutral comet in an electrically neutral solar system. It is no longer useful to ignore the electrical properties of plasma.

Astronomers have calculated the mass and density of comets from the effects they have on the trajectories of various spacecraft. By this reasoning comet Halley’s nucleus had a density of only 0.1 to 0.25 that of water. But such conclusions are immediately invalidated if comets are electrically charged bodies moving through an electric field of the Sun. Where charged bodies interact across a plasma medium, all common assumptions about gravity become suspect.

Most larger comet nuclei do not exceed one billionth of the mass of Earth. Hence, even under the standard assumptions, a comet’s gravity is insufficient to do the things that comet investigators, confronted with new surprises, ask it to do. Look at the surface of Comet Wild 2, for example. When they first saw the pictures of the comet, a number of scientists declared that the craters were the result of impacts. But a small rock will not attract impactors, and in view of the emptiness of space, even in the hypothetical “planet-forming nebula” stage, it is inconceivable that such a small body could have been subjected to enough projectiles to cover it, end to end, with craters. Nor is it plausible to imagine a melting snowball or iceberg retaining such impact structures from primordial times. Sublimating ice quickly loses its distinctive features.

Some astronomers suggested that the craters were sinkholes, formed when surface material fell into cavities left by the sublimation of volatiles. But is it reasonable to ask the minuscule gravity of a comet nucleus to produce “sinkholes” in this fashion?

The frequent erratic motions of comets—in apparent violation of gravitational laws—have long been attributed to the “jets” seen erupting from the nucleus. The distinguished astronomer Fred Whipple first suggested that jets from comets could account for unpredictable motions. 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”.

As Comet Linear moved toward perihelion, a NASA release stated, “powerful jets of gas vaporized by solar radiation have been pushing the comet to and fro”. Astronomers applied the same interpretation to the energetic jets of Borrelly and Wild 2. But in the case of Wild 2 (see link above), the close-up photographs gave no indication of caverns in which selective heating by the Sun could build up the pressures of “jet chambers” or produce the sonic and supersonic jet velocities our instruments have measured. And yet today, the astronomers’ dogma holds: “What else could these jets be”? To save the theory astronomers cling to the incredible.

From an electric viewpoint there is no enigma in these comet attributes. The jets are not released under pressure but are created by electric arcs to the surface, and it is these arcs that carve out the surface craters. The jets do not explode from hidden areas within the nucleus. In the best photos ever of a comet, Wild 2 (link above), no such caverns are evident. Rather, we see hot spots on high points and on the rims of shallow, flat-bottomed craters.

By now it should be obvious that something more than gravity is at work in the behavior of comets. Since a comet holds a highly negative charge, it attracts the positively charged particles of the solar wind, giving rise to an immense envelope of ionized hydrogen, up to millions of miles across. But the comet watchers do not realize that this vast envelope is gathered and held electrically. And so the question continues to haunt them: How could a tiny piece of rock, no more than a few miles wide, gravitationally entrain and hold in place a ten million mile wide bubble of hydrogen against the force of the solar wind? Yes, the entrained envelope is extremely diffuse, but in gravitational terms it should not be there!

If the electric theorists are correct, there is no mystery in the gravity-defying behavior of comets. A gravitationally insignificant rock on a highly elliptical orbit can be an electrically powerful object.

See also: Comets


David Talbott, Wallace Thornhill
Amy Acheson
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