QUESTIONS WITH SOLUTIONS GRADED A+
◉Consider again the portion of the video discussed in Part A. Notice
that in the view through the camera, the parallax is larger (the apparent
movement is larger) for the man than for the trees, and that the
mountains do not appear to shift at all. Why? Answer: The amount of
parallax depends on an object's distance, with larger parallax for nearer
objects.
◉Just as you found for parallax on Earth, stellar parallax is larger for
stars that are nearer and smaller for stars that ar more distant. Which
statement best summarizes why stellar parallax occurs? You may find it
helpful to watch the animation of stellar parallax that begins at about
1:20 into the video. Answer: We view nearby stars from different
positions in Earth's orbit at different times of year.
◉Observations of stellar parallax therefore provide direct evidence that:
Answer: -Some stars are more distant than others
-Earth orbits the Sun
, ◉As you saw in Part D, stellar parallax exists only because Earth orbits
the Sun. Therefore, if the ancient Greeks had measured stellar parallax,
they would have known that their belief in an Earth-centered universe
was wrong. Why didn't the ancient Greeks measure stellar parallax?
Answer: Even for the nearest stars, parallax angles are too small to
measure with the naked eye.
◉Based on their inability to detect stellar parallax, the ancient Greeks
concluded that _________. Answer: either Earth is the center of the
universe or stars are extremely far away
◉As discussed in the video, parallax measurements allow us to calculate
distances to stars for which parallax is detectable. Suppose you have a
telescope capable of measuring parallax shifts of a particular amount
(for example, 0.001 arcsecond). Which of the following locations for the
telescope would allow you to measure distances to the most distant
stars? Answer: a telescope on Mars
◉On the main screen of the interactive figure, select "Parallax", then
select the "Introduction to Parallax" button. Click the play button to
watch the animation, and watch how the motion of the photographer
(lower window) affects what the camera sees (upper window). Which of
the following statements correctly describes what is really happening?
(Note: You need not continue with the next button to answer this
question.) Answer: The photographer is moving, but the person being
photographed and the trees are staying still.