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Explorations an Introduction to Astronomy Thomas T. Arny | ||||||||
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Chapter
Images
Chapter 16, Figure 25
Figure
16.25
Sketch illustrating
that when a light source turns on, we see the light from its near side before
we see the light from its far side, and so we do not see its light turn on instantly. For the
objects that we encounter in everyday life, the time delay is so short we
do not notice it. However, for astronomical-sized bodies the effect can create
delays ranging from days to months, from which we can deduce that the emitting
body is light-days or light-months across.
