What happens when a main-sequence star exhausts its core hydrogen fuel supply?
A) The entire star shrinks in size.
B) The core shrinks while the rest of the star expands.
C) The core immediately begins to fuse its helium into carbon.
D) The star becomes a neutron star.
B
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Which of the following would be the strongest clue that a rock you have found is a meteorite rather than a terrestrial rock?
A) It contains a lot of iron. B) It is dark colored. C) It contains elements and isotopes in proportions that are rare on Earth but common in asteroids. D) It is too heavy for you to hold in your hand.
Suppose we discover a new comet on an orbit that brings it closer to the Sun than Mercury every 125 years. What can we conclude?
A) It has a coma and tail during most of each orbit. B) It came from the Kuiper belt. C) It has been on its current orbit for only a very short time compared to the age of our solar system. D) It came from the Oort cloud.
When it is summer in the Northern Hemisphere, it is ________ in the Southern Hemisphere.
A) winter B) fall C) spring D) summer
Which stellar spectral type has strong molecular absorption lines in its optical spectrum?
A) M B) G C) K D) O E) B