Details Relating to the Revised Oort Cloud Theory
46. 
Formation Mechanism,
Heavy Hydrogen. Same as item 30 on page 333.
47.
Ice on Moon and Mercury. Same as item 14 on page 332.
48.
Crystalline Dust. Same as item 32 on page 334.
49. 
Near-Parabolic Comets. See item 33.
50.
Random Perihelion Directions. See item 34.
51.
No Incoming Hyperbolic Orbits. Same as item 35 on page 334.
52.
Small Perihelions. Same as item 36 on page 334.
53.
Two Separate Populations. Short-period comets might be explained if comets formed near the giant planets. However, this would not produce the number of needed near-parabolic comets. The average comet flung out toward an Oort cloud, but not expelled from the solar system, would end up far short of where the Oort cloud supposedly is.126 [See Figure 12 on page 318.]
54.
Jupiter’s Family. Comets in Jupiter’s family have an average life span of only about 12,000 years. They could not have accumulated over millions of years.
55.
High Loss Rates of Comets. Several locations for cometary nurseries in the giant-planet region have been proposed. Oort favored the asteroid belt, between Mars and Jupiter, if such a nursery was needed to supply the Oort cloud. Later, Fernández showed that, if comets were born near Jupiter, Jupiter would expel too many from the solar system. To account for today’s high loss rate of comets from an Oort cloud would require 10,000 Earth masses of comets in a Jupiter birthing region 4.5-billion years ago—“too large to consider it dynamically reasonable.” 127 Jupiter would have to fling 30 times its mass out to the Oort cloud ! No planet’s energy and angular momentum could have done the job.128
Fernández favored the region between Uranus and Neptune as the place where comets were born and steadily flung out to the Oort cloud. This would require the least amount of cometary birthing material—about 17 Earth masses—or the mass of Neptune. However, Uranus and Neptune would probably not have had the necessary energy and angular momentum.
Overcrowding is another problem. If so many comets began in the giant planet region, they would often collide and fragment. Only about 5% of the comets needed by an Oort cloud could have been delivered to the Oort cloud.129
Öpik raised a more serious problem. To form comets in the Uranus-Neptune region and then eject them out to an Oort cloud would require about 100-billion years—20 times the assumed age of the solar system.130
In 1950, Gerard Kuiper (KI-per) theorized that material that almost formed a planet should still exist beyond Neptune, 35–50 AU from the Sun.131 This region, which some believe is filled with comets, is now called the Kuiper Belt. Kuiper thought that Pluto expelled the nursery’s comets out to the Oort cloud. Later it was learned that Pluto’s mass was much too small for the job.
Since 1992, ground-based telescopes, the Hubble Space Telescope, and other techniques have detected more than 70,000 large objects in the Kuiper Belt,109 a region that some had hoped was the source of comets in the solar system and in the Oort cloud. Later, it was realized that these objects were ten times too large (30 – 1,500 miles in diameter) to be comets and too few in number. A reexamination of that region of the sky by the Hubble Space Telescope has failed to detect a comet reservoir.132 Besides, the hydroplate theory provides a simple explanation for the Kuiper Belt. [See “The Origin of Trans-Neptunian Objects (TNOs)” on page 359.]
56.
Composition. Same as item 40 on page 335.
57.
Small Comets. See item 17 on page 332.
58.
Recent Meteor Streams. See item 9 on page 331.
59.
Crater Ages. This theory requires a comet nursery containing at least 1013 comets.133 As the giant planets fling some comets out to an Oort cloud, other comets would frequently bombard Earth from close range. The further back in time, the greater the bombardment rate. As with the original Oort cloud theory, craters from this intense bombardment should be increasingly visible the deeper one looks in Earth’s sedimentary layers. Instead, craters are almost exclusively found in surface layers.
60.
Other/Missing Star. Same as item 44 on page 335.