Difficulties
This lunar origin hypothesis has some difficulties that have yet to be fully resolved. For example, the giant impact hypothesis implies that a surface magma ocean would have formed following the impact. Yet there is no evidence that the Earth ever had such a magma ocean and it is likely there exists material that has never been processed by a magma ocean.
Read more about this topic: Giant Impact Hypothesis
Famous quotes containing the word difficulties:
“Our achievements speak for themselves. What we have to keep track of are our failures, discouragements, and doubts. We tend to forget the past difficulties, the many false starts, and the painful groping. We see our past achievements as the end result of a clean forward thrust, and our present difficulties as signs of decline and decay.”
—Eric Hoffer (1902–1983)
“The intellectual life may be kept clean and healthful, if man will live the life of nature, and not import into his mind difficulties which are none of his.”
—Ralph Waldo Emerson (1803–1882)
“Only a great actor finds the difficulties of the actor’s art infinite.”
—Ellen Terry (1847–1928)