The extinction of starlight due to the interstellar medium 
Definitions:
Ego Defenses
Psychological strategies employed by the ego to manage anxiety, conflict, and internal or external stressors.
Id Impulses
Instinctual drives and desires, often unconscious, that form part of Freud's structural model of the psyche, seeking immediate satisfaction according to the pleasure principle.
Ego Defense Mechanisms
According to psychoanalytic theory, strategies developed by the ego to control unacceptable id impulses and to avoid or reduce the anxiety they arouse.
Unconscious Conflict
A struggle or problem that exists in one's unconscious mind, affecting behavior and emotions without the individual's awareness.
Q1: What distance method did Edwin Hubble use
Q19: Massive planets create _ doppler shifts of
Q25: Refer to Table 9-1.The star HR 4621
Q31: Each photon a radio telescope collects has
Q39: Which of the following observations would support
Q40: Many classical astronomers believed Earth could not
Q49: The first scientific attempt to map the
Q52: The Ptolemaic model of the universe was
Q60: Which of the following can be determined
Q74: Which star in Diagram 9-1 has the