Which of the following techniques could allow astronomers to observe the structures in the Universe during the Dark Ages?
A) blackbody emission
B) the H-alpha line
C) the 21-cm-line
D) molecular lines

Question

Quizplus · Accepted Answer

The 21-cm-line radiation is emitted when the spin state of a hydrogen atom changes from aligned to anti-aligned. This radiation can pass through the Universe without being absorbed by intervening matter, allowing us to observe structures during the Dark Ages.

Which of the Following Techniques Could Allow Astronomers to Observe