Explain how Edwin Hubble used Cepheid variables to change our view of the structure of the universe
What will be an ideal response?
Cepheid variables are extremely bright variable stars that increase and decrease in brightness in a repetitive cycle. This group of stars is significant because their "true" brightness, called absolute magnitude, can be determined by knowing the rate at which they pulsate. When the absolute magnitude of a star is compared to its observed brightness, a reliable approximation of distance can be established. Thus, Cepheid variables are important because they can be used to measure large astronomical distances. Hubble observed the Andromeda galaxy, beyond the Milky Way, and used his observations to determine that the universe extended "far beyond the limits of our imagination."
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A) mass. B) weight. C) radial distance. D) all of the above E) none of the above
A glacial outburst flood is also called a(n) _______________
Indicate whether this statement is true or false.
The International Panel on Climate Change is made up of over 2,500 atmospheric scientists from over 130 countries around the world
Indicate whether the statement is true or false
How does Earth as a planet compare to an orbiting space station in terms of providing a life support system for its inhabitants? Other than size, what are some of their differences and similarities in terms of habitation?