How do astronomers observe the first galaxies in the universe?
Quick Answer
They use powerful telescopes to detect extremely faint, redshifted light from very distant objects. Because of cosmic expansion, much of that light arrives in infrared wavelengths.
The Full Story
The first galaxies are so distant that their light has taken more than 13 billion years to reach us and has been stretched by the expansion of the universe. That means astronomers need sensitive infrared observations to find them. The Hubble Space Telescope opened this field with deep surveys, and the James Webb Space Telescope has pushed even farther back in time since 2022. Researchers search for high-redshift galaxies by looking for distinctive breaks in their spectra caused by hydrogen absorption. These observations help scientists study how early star formation and reionization began.
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Suggested video title for this topic:
"Seeing galaxies from the dawn of time"
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