a . “Planet formation is a paradox: according to standard theory, dust grains orbiting newborn stars should spiral into those stars rather than accrete to form planets.” Philip Campbell, “Trap Holds Protoplanet Dust,” Nature, Vol. 498, 13 June 2013, p. 141.
u Very special conditions are required to capture and then merge orbiting bodies. They are discussed more fully starting on page 312.
b . John F. Kerridge and James F. Vedder, “An Experimental Approach to Circumsolar Accretion,” Symposium on the Origin of the Solar System (Paris, France: Centre National de la Recherche Scientifique, 1972), pp. 282–283.
u “It turns out to be surprisingly difficult for planetesimals to accrete mass during even the most gentle collisions.” Erik Asphaug, “The Small Planets,” Scientific American, Vol. 282, May 2000, p. 54.
u “But little is known about how microscopic dust particles can grow 14 orders of magnitude bigger to become a giant planet within the relatively short lifetime of the disk.” Zhaohuan Zhu, “Growing Planet Brought to Light,” Nature, Vol. 527, 19 November 2015, p. 310.
c . Tim Folger, “This Battered Earth,” Discover, January 1994, p. 33.
u “‘We came to the conclusion,’ says Lissauer, ‘that if you accrete planets from a uniform disk of planetesimals, [the observed] prograde rotation just can’t be explained.’ The simulated bombardment leaves a growing planet spinning once a week at most, not once a day.” Richard A. Kerr, “Theoreticians Are Putting a New Spin on the Planets,” Science, Vol. 258, 23 October 1992, p. 548.
u Luke Dones and Scott Tremaine, “Why Does the Earth Spin Forward?” Science, Vol. 259, 15 January 1993, pp. 350 –354.
u Some believe that the inner planets (Mercury, Venus, Earth, and Mars) gained their spins through a few very large and improbable impacts. However, this appeal to large, improbable impacts will not work for the giant outer planets (Jupiter, Saturn, Uranus, and Neptune), which have the most spin energy. Such impacts on these gaseous planets would be even more improbable, because they move more slowly and are so far from the center of the solar system. Besides, impacts from large rocks would not account for the composition of the giant planets—primarily hydrogen and helium.
d . “Building Jupiter has long been a problem to theorists.” George W. Wetherill, “How Special Is Jupiter?” Nature, Vol. 373, 9 February 1995, p. 470.
u “Talk about a major embarrassment for planetary scientists. There, blazing away in the late evening sky, are Jupiter and Saturn—the gas giants that account for 93% of the solar system’s planetary mass—and no one has a satisfying explanation of how they were made.” Richard A. Kerr, “A Quickie Birth for Jupiters and Saturns,” Science, Vol. 298, 29 November 2002, p. 1698.
e . This idea has a further difficulty. If, as the solar system began to form, a large, rocky planet quickly formed near Jupiter’s orbit, why didn’t a rocky planet form in the adjacent asteroid belt where we see more than 200,000 rocky bodies (asteroids) today?
f . B. Zuckerman et al., “Inhibition of Giant-Planet Formation by Rapid Gas Depletion around Young Stars,” Nature, Vol. 373, 9 February 1995, pp. 494–496.
g . “In the best simulations of the process [of evolving Uranus and Neptune], cores for Uranus and Neptune fail to form at their present positions in even 4.5-billion years, [what evolutionists believe is] the lifetime of the solar system. ‘Things just grow too slowly’ in the outermost solar system, says Weidenschilling. ‘We’ve tried to form Uranus and Neptune at their present locations and failed miserably.’ ” Stuart Weidenschilling, as quoted by Richard A. Kerr, “Shaking Up a Nursery of Giant Planets,” Science, Vol. 286, 10 December 1999, p. 2054.
u Renu Malhotra, “Chaotic Planet Formation,” Nature, Vol. 402, 9 December 1999, pp. 599–600.