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Redshift

Redshift is the phenomenon where light from distant galaxies is stretched to longer, redder wavelengths due to the expansion of the universe. It serves as a key observational evidence for the universe's ongoing expansion.

Source: science.nasa.gov

APODs including "Redshift"

Mystery: Little Red Dots in the Early Universe

24/12/2025

Mystery: Little Red Dots in the Early Universe
Image Credit: NASA Astronomy Picture of the Day

What are these little red dots (LRDs)? Nobody knows. Discovered only last year, hundreds of LRDs have now been found by the James Webb Space Telescope in the early universe. Although extremely faint, LRDs are now frequently identified in deep observations made for other purposes. A wide-ranging debate is raging about what LRDs may be and what importance they may have. Possible origin hypotheses include accreting supermassive black holes inside clouds of gas and dust, bursts of star formation in young dust-reddened galaxies, and dark matter powered gas clouds. The highlighted images show six nearly featureless LRDs listed under the JWST program that found them, and z, a distance indicator called cosmological redshift. Additionally, searches are underway in our nearby universe to try to find whatever previous LRDs might have become today.