In your own words, explain how astronomers determined that the universe is expanding
What will be an ideal response?
The best observation we can make to determine that the universe is expanding is based on the Doppler effect: the red shift. When we look at galaxies relative to each other, we can look at the light emanating from them. When this source of light is moving away from the observer, it is stretched, and this produces light of a longer wavelength. Longer-wavelength light is redder (shorter-wavelength light is bluer). Thus, by observing light shifting toward the red spectrum, we know it is being stretched, which in turn means it is moving away, which in turn means the universe is expanding.
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The development that set the stage for the evolution of animals that lived entirely on the land was the ____________________
Fill in the blank(s) with correct word
Briefly describe the sector model for the internal social structure of cities
What will be an ideal response?
Indian reservations are among the poorest communities in the U.S
a. True b. False Indicate whether the statement is true or false
Which data were used to develop the hypothesis of continental drift?
A. the distribution of glacial deposits and directions of glacial scratch marks B. the shape of the continents C. the distribution of fossils D. All of these choices are correct.