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Home Q & A Board Science-Related Homework Help Physics
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symbo symbo
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7 years ago
Why would intelligent alien beings wanting to communicate with us probably choose the 21-cm atomic hydrogen radio wavelength?
A)   Because this wavelength shows a very strong Doppler effect when its source is moving, and they would know that we would be able to detect the orbital motion of their home planet around their star by this method
B)   Because they would expect that many of our telescopes would already be tuned to this precise wavelength for scientific work
C)   Because this radiation at this particular wavelength is very weak from natural sources in space and messages would be easily distinguished from other sources
D)   Because they would have detected this particular wavelength from our transmitters on the Earth since it is used extensively for satellite communications, and they would know that we could detect them easily
Textbook 
Discovering the Universe

Discovering the Universe


Edition: 7th
Authors:
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hyponoticahyponotica
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7 years ago
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symbo Author
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#2
6 years ago
Thanks for answering, I'll share this with my classmates too
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