Some globular clusters have three main sequence tracks. This indicates:
A) three different stellar compositions.
B) three episodes of star formation, separated by billions of years.
C) stars evolve through three different mechanisms.
D) the stars were observed from three different telescopes.
Question 2
Compared to optical telescopes, radio telescopes are built large because:
A) they're less expensive to make than optical telescopes.
B) radio photons don't carry much energy.
C) atmospheric turbulence is more of a problem.
D) radio sources are harder to find.
E) radio waves are absorbed by the atmosphere.
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