As discussed in the Extraordinary Claims box, when the giant impact idea was first proposed, it was generally thought to be so unlikely that it wasn’t seriously considered until decades later, after the Apollo missions to the Moon. What key piece of scientific understanding was missing that made it seem so unlikely when first proposed?
a. An understanding of the number and size of leftover planetesimals in the early solar system.
b. An understanding of how heavily cratered the Moon’s surface is.
c. A precise age for the solar system.
d. An understanding of the difficulty of gravitationally capturing a body as large as our Moon.
Answer : a. An understanding of the number and size of leftover planetesimals in the early solar system.
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No stars have been found composed solely of Hydrogen and Helium (and no heavier elements)
Indicate whether the statement is true or false
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A. 5.4 × 10-4 m3/s B. 5.4 × 10-5 m3/s C. 5.4 × 10-6 m3/s D. 5.4 × 10-7 m3/s