Suppose a future astronaut travels to a distance planet around a distant star. They collect rocks for dating the age of the planet and system. The astronaut compares the abundance of a certain radioactive element (half life of element = 500 million years) in the collected rocks to the abundance of the same element in a newly formed rock. They measure that there are 1/16th the number of radioactive atoms in the collected sample. How old is this planet? a. 8 billion years old.
b. 4 billion years old.
c. 1 billion years old.
d. 2 billion years old.
e. 16 billion years old.