Sample PagesAlthough the occurrence of such events in the past would not be detectable from planetary motions today, wouldn't we expect to find evidence of such colossal electrical interactions written across their surfaces? The debate over volcanic versus impact theories to explain the craters on the Moon and other bodies of the Solar System goes back a long time. Although impact is the currently favored alternative, neither can fully explain all the features that are found. These include such recurring characteristics as craters with central peaks; flat, melted, glassy floors; and terraced walls, with the terraces again in some instances showing signs of melting. And then, along with craters, there are long, sinuous rilles and furrows; concatenated chains of craterlets--frequently scalloping the rims of larger craters; and raised blister domes, sometimes with burnt appearances.
Impacts cause very little melting. The pulverized rock tends to flow like a liquid under the overpressure and then freezes in a starburst pattern, leaving typically non-circular, dish-shaped craters with gently sloping walls. Laboratory simulations and experiments with explosives have consistently failed to reproduce the complex structures observed. But even down to the finer details, the marks and scars seen all over the Solar System bear an uncanny resemblance to phenomena produced routinely in electric spark machining, where material is removed by the focused energy of an electric arc discharge.
An arc discharge takes place when the electric field between two charged objects, a negative "cathode" and a positive "anode," is strong enough to accelerate charged ions of the intervening material to energies that ionize more atoms by collision, resulting in an avalanching current and breakdown of resistance. Common examples are arc welding, lightning discharges between clouds and the ground, and the lower-voltage glow of a neon tube.
The two ends of an arc behave differently. An anode discharge sticks to one point on the anode surface, producing intense heat and melting, with a tendency for the arc to move around the center point in a corkscrew motion, scouring a crater and throwing up a steep-sided, circular rim. Terraced walls are common, depending on conditions, as are conical central mounds, which tend to be left in larger craters in a way similar to the raised "fulgamite" blistering found on lighting conductors after a strike.
Scaled-up analogs of all these features are found across the Solar System, from the Moon, Mars, Venus, and Mercury to other satellites and the Asteroids. Some asteroids exhibit craters that are surely too large to have been produced by an impact without shattering the entire body. Mathilde shows five huge craters ranging from 3/4 to 1-1/4 times its mean radius. Vesta, 530 km diameter, has a gigantic circular crater 460 km across with a 13 km high central peak, yet the rest of its surface appears to be intact. Since impacts are the in-fashion at the moment, elaborate mechanisms are contrived to find explanations that will fit. But such anomalies as the stratified central peak of the large buried Sudbury crater in Canada, thorium enrichment of the crater rim at Wolfe Creek in Western Australia (sufficiently powerful discharges can initiate transmutation of elements), and the "shatter cone" structure of the rim of the 70 km wide Vredefort Dome in South Africa seem more readily compatible with an electrical interpretation.
Cathode discharges wander across the surface, typically between higher points where field intensity is more concentrated, and blast linear, snaking features. Chains of circular pits and craters are common, sometimes following the rim of a larger crater just formed. Explosive discharges channeled underground can be extremely effective excavating agents. Again, the Moon, Mars, and other bodies are scarred with rilles and grooves tracing their own course without regard for the structure or slope of the pre-existing terrain. The record is held by Venus with a gouge winding 6,800 km over hill and dale, and a steady 2 km wide. It's described officially as a "collapsed lava tube." At the other extreme we find rilles on the 20 km rock Phobos, one of the moons of Mars. Presumably this would have to be ascribed to inner geological activity.
Something removed two million cubic kilometers of material from Mars to create the stupendous Valles Marineris canyon, running a quarter of the way around the planet. This could perhaps help explain the rock-strewn appearance of large areas of the surface, discoveries of Martian meteorites on Earth, and maybe the origin of many of asteroids, meteorites, and other bodies. Interestingly, ancient myths and legends worldwide tell of a thunderbolt striking the Mars god and leaving a scar in his cheek, brow, or thigh--the implication being that the planets at that time came sufficiently close for the event to be visible.
From high above, the tracery of ridges and gorges around the Grand Canyon is strikingly (pun accidental; you can't avoid them when getting into this subject) evocative of "Lichtenberg figures" frequently etched into the ground after a powerful lightning discharge.
Io, the innermost Galilean moon of Jupiter, is very likely in the process of undergoing arc machining right now, under the eyes of NASA space probes. Except that the ejection of hot matter plumes 800 km into space with hot-spot temperatures second only to the surface of the Sun, fallout patterns of perfect concentric circles, and an apparently inexhaustible supply of volatile materials, are all attributed to volcanoes. The power to drive this is said to be tidal heating as Io rises and falls 100m through Jupiter's gravity field in its mildly eccentric orbit. Plumes have been followed migrating across the surface and leaving chains of small circular craters--one plume is measured as having wandered 85 km between 1979 and 1996. This is explained by some spokespeople as due to the vaporizing of "snowfields" of sulfur dioxide or sulfur by lava flows, and by others as"mantle plumes" of hot rising masses deep in the interior. Why the plumes should display a filamentary structure--the hallmark of plasmas conducting current--and how they come to exist without any connection to visible volcanic calderas remain unaccounted for. Proponents of an electrical model have no difficulty recognizing all of these features as indicative of an arc discharge in action between Io and Jupiter.
Io has been called "the great pizza in the sky" because of its orange, yellow, and red blotchy appearance, which is due to vast quantities of sulfur compounds covering the surface. Exotic chemical processes in the interior have been concocted to explain this abundance, all premised on the assumption of volcanoes. But if the jets mark the points of impinging cathode discharges, a more likely explanation would be that sulfur atoms are being produced by the combining of two oxygen atoms in the powerful field of the arc. Water ice, which occurs on all the other Galilean satellites of Jupiter, would provide a ready source of oxygen. The icy surface of Europa is covered by a network of furrows and grooves that are supposedly "cracks." Larger ones show regions of reddish coloring along the edges, and readings from the Galileo probe indicate a significant presence of sulfuric acid. A NASA researcher described the findings as demonstrating Europa to be "a really bizarre place." Not really.