GK
BIG BANG THEORY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The sun
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A Cepheid variable
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A shiny rock
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Light year
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Detailed explanation-1: -Cepheid variables are pulsating stars that brighten and fade in a predictable pattern. The illustrated graph shows that V1 completes a pulsation cycle every 31.4 days.
Detailed explanation-2: -Cepheids are reasonably abundant and very bright. Astronomers can identify them not only in our Galaxy, but in other nearby galaxies as well. If one requires the distance to a given galaxy one first locates the Cepheid variables in this galaxy.
Detailed explanation-3: -Cepheid variable stars are intrinsic variables which pulsate in a predicatable way. In addition, a Cepheid star’s period (how often it pulsates) is directly related to its luminosity or brightness. Cepheid variables are extremely luminous and very distant ones can be observed and measured.