Comets, the Kuiper Belt and the Oort Cloud

Abstract: With the development of modern space-based telescopes and the past decade or more of collection of data on both comets and celestial bodies found to orbit the sun at distance greater than that of the planet Neptune, a review of the current data suggests that there can be no longer any doubt that the Kuiper belt does exist. Though, the objects contained therein probably more rightly should be called Trans-Neptunian objects because there is no reason that the solar system ends at Neptune and a new region of space begins. However, there is no evidence that the putative Oort exists. The Kuiper belt was originally believed to be the primary source, from which the Oort cloud was populated, over the alleged 4.6 billion year history since our solar system formed. The latter still has not been found, yet it is critically needed as the only source of long-period comets for the uniformitarian theory.  However, I suggest that the existence of short-period comets as a young solar system argument may no longer be tenable.  (Accepted September 21, 2016, published January 17, 2017 in Creation Research Society Quarterly 53:5–13, 2016, PDF with colour figures.)

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Comets were once thought to be atmospheric phenomena, and there was a time when they were believed to be harbingers of doom.1 Comets are now known to be dirty balls of ices and dust and some even icy dirt balls.2 They travel into the inner solar system displaying, in some cases spectacularly, their long tails, which comprise escaping gas and dust, sublimating3 from their icy surface. This display gets stronger as they approach the sun where the sun’s radiation has a very strong effect on the volatile chemicals in the ball of ice. Driven away from the sun, by radiation pressure and the solar wind, this loss of material depletes the mass of the comet. Some comets have relatively short orbital periods of less than 200 years, whereas others have periods much longer than 200 years. This has become a convenient basis for classifying a comet short-period or long-period. However the more significant criteria of classification is their orbital characteristics: inclination and whether prograde or retrograde in their orbital trajectories.

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Figure 1: Comet C/2012 S1 (ISON) April 30, 2013. The comet was 3.9 AU (580 million km) from the sun and 4.3 AU (640 million km) from Earth. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

The Bible gives an age of the solar system and the universe of around 6000 years, but the nebular hypothesis proposes that the solar system began condensing from a giant collapsing cloud of molecular hydrogenand dust about 5 billion years ago and the material of comets formed about 4.6 billion years ago. However, based on the known loss rate of the material from observed comets, there should be no short period comets left.5,6

A typical comet (5 – 10 km in diameter) has a mass of 5 – 10 × 1014 kg. That may seem like a lot but comets lose tens of tons of material per second on approach to the sun. The comet Halley at its peak loss rate loses about 54 tons/second of gas including gas from volatile ices, at a distance of about 1 AU7 from the sun. Assuming the process only occurs during one third of its orbit—the portion when it is closest to the sun—a comet loses about 5.7 × 1011 kg/passage, which means it could only survive 95 passages around the sun before there is no matter left.8

Assuming that a comet is sourced from the original material from the creation of the solar system, if it passes the sun once in 200 years it could only pass 30 times in the biblical lifetime of the solar system, which is completely within expectation. In fact, it would only be 30% depleted of its initial mass. That means it still has 65 more passages left before all the material from its nucleus would be lost. But how could it pass 25 million times as required in the uniformitarian lifetime of the solar system? There is the problem. Why do short-period comets still exist if the nebular hypothesis is the true description of the formation of the solar system? Quite obviously this problem does not exist for the biblical creationist.

Long-period comets might have a period from a hundred thousand years up to a million years, it is alleged. But if they too can only survive 95 passages around the sun, they have at most only 95 million years of total life.9 So, why are there still any long-period comets? From the perspective of the uniformitarian nebular hypothesis, where do they come from? Continue reading