Changes

"No one knows quite how planetesimals ever attain protoplanet status." (D. Kaisler, The puzzles of planethood, Sky & Telescope 104(2):32-38, 2002. <ref>http://www.creationscience.com/onlinebook/ReferencesandNotes46.html</ref>

"No one knows quite how planetesimals ever attain protoplanet status." (D. Kaisler, The puzzles of planethood, Sky & Telescope 104(2):32-38, 2002.  

“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.

“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. <ref>http://www.creationscience.com/onlinebook/ReferencesandNotes46.html</ref>

== References ==

== References ==