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the Facts & Faith, Third Quarter
1997 Issue (Vol. 11, No. 3)by Guillermo Gonzalez
In this era of minivans and mini-series, why not "minicomets"? The name seems appropriate to the newly discovered class of comets bombarding Earth’s upper atmosphere at the incredible rate of one every three to four seconds. While a thousand times smaller than classical comets, such as Halley, minicomets vastly outnumber their larger cousins.1
Not all researchers are convinced yet, but if these minicomets behave as recent theory suggests, they help explain at least four profound mysteries:
Louis Frank, of the University of Iowa, first suggested the existence of minicomets in the 1980’s. He proposed them as an explanation for the dark spots on ultraviolet images of the upper atmosphere sent back from the Dynamics Explorer 1 satellite. In keeping with a number of observational constraints, Frank and his colleagues hypothesized the existence of 30-ton slush balls, loosely-packed watery ice with a dark shell, giving them a low reflectivity before breakup.2 This hypothesis met with much skepticism (for a brief review of the initial debate, see reference 3) for more than a decade. Last May, however, Dr. Frank released images obtained by the Polar satellite in 1996 that have all but silenced his foes.4, 5, 6
Minicomets explain how water arrives (from above!) at the layer where noctilucent clouds form. Ordinary meteors supply the dust particles around which the drops condense.7
Minicomets explain the apparent correlation between the earth’s orbital inclination (tilt) and its ice volume over the last million years. If the minicomets are concentrated along the ecliptic plane (the plane of the sun’s orbital path through space), the rate of minicomet influx will be afftected by variations in earth’s orbital inclination—the lowest inclinations leading to the greatest influx rates.8
If Dr. Frank’s numbers are correct, minicomets could also account for all of the world’s oceans arising in about a billion years, extrapolating from the current influx rate. Even if his numbers are too large, minicomets still can be credited with supplying a significant portion of the planet’s ocean water. If this supply of water from the minicomets were shut off, the earth’s oceans would be lost in just a few billion years by "mantle subduction," one crustal plate’s edge sliding under the edge of an adjacent plate.
The supply of water (and some carbon dioxide and methane) brought to Earth by minicomets would also significantly influence the planet’s temperature. Given the greenhouse effect, increased influx rates should result in increased temperatures. Carbon dioxide and methane are removed from the atmosphere by a combination of volcanic, tectonic, chemical, gravitational, and biological processes on the earth’s surface. An extraterrestrial source for replenishment of these light chemicals would help balance their depletion, thus balancing Earth’s surface temperature, a necessity for life support. But the supply must come in at just the right rate: too much, and the earth gets too hot from the greenhouse effect; too little, and the earth would grow cold and dry.
Since the influx rate of minicomets cannot be directly affected by the rates of tectonic, volcanic, and chemical activity, by the strength of the earth’s gravity, or by the quantity and kinds of biological activity, the required balances among all these processes is all the more remarkable. In addition, the minicomet influx rate must decrease throughout the past 4.5 billion years to balance the effects of the sun’s 30 percent brightening in that time9 and also to balance the decrease in the rates of both vulcanism and tectonic activity.10-11 Eventually, we may be able to correlate abrupt changes in this inclux rate to dramatic climatic variations through Earth’s history.
Climatologists have long held the view that the earth’s temperature maintains itself within a tolerable range for life by some kind of "self-regulating system" that balances weathering, the removal of carbon dioxide from the atmosphere, and volcanic outgassing, the replenishment of it.12 Today we must acknowledge, however, that the situation is far more complex. The earth’s habitability is dependent on more than a few terrestrial processes. And, its habitability is closely tied to events occurring at distances ranging from thousands of kilometers to millions of light years.
The theological implications seem obvious. We cannot, in this case, suggest that these balances just happened to fall into place for support of life because life itself—its quantity, diversity, distribution, and biochemical impact—is one of the balancing factors. I see no way for life, unless governed by a super-intelligent Creator, to predict and respond perfectly to ongoing changes in the other balanced features. Life is so information rich13 and its environment so narrowly defined14 as to defy strictly natural explanation. The personal involvement of a supernatural Creator seems scientifically reasonable to me.
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1997 Issue (Vol. 11, No. 3)