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Galaxy cluster Abell 2744 (Pandora’s Cluster), with X-ray emissions in red. Credit: NASA, ESA, ESO, CXC and D. COE (STSCI) J. Merten (Heidelberg/Bologna) If redshift equals distance calculations are incorrect, the Universe could be a much different looking place. “Of course, if one ignores contradictory observations, one can claim to have an ‘elegant’ or ‘robust’ theory. But it isn’t science.” — Halton Arp The speed of light is used as a benchmark for defining cosmological distance calculations. As discussed in past Picture of the Day articles, the shifting of Fraunhofer lines into the red end of electromagnetic spectra is...

Explanation: Why is this cluster of galaxies so jumbled? Far from a smooth distribution, Abell 2744 not only has knots of galaxies, but the X-ray emitting hot gas (colored red) in the cluster appears distributed differently than the dark matter. The dark matter, taking up over 75 percent of the cluster mass and colored blue in the above image, was inferred by that needed to create the distortion of background galaxies by gravitational lensing. The jumble appears to result from the slow motion collision of at least four smaller galaxy clusters over the past few billion years. The above picture...