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Name: Katy T.
Status: Educator
Age: 20s
Location: N/A
Country: N/A
Date: February 23, 2003

How are distances from the Earth to specific galaxies calculated? I know it is determined employing the speed of light in a year. But how can the time it takes to leave the source galaxy be measured?


The light coming from the galaxy or a star experiences a shift in frequency spectrum towards longer wavelengths, commonly called the "red shift". The greater the shift the greater the distance away the galaxy is.

Search the Internet for the term "red shift" and you will find more detailed information.

David R. Cook
Atmospheric Research Section
Environmental Research Division
Argonne National Laboratory

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