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Experimental hall of the KATRIN experiment showing the main spectrometer from the front. The outside rings are air-coil magnets used to compensate for the earth's magnetic field. Reiner Kruecken Collage of a black and white finger holding a microchip on top of a colorful background of painterly strokes Graphic collage of a person standing in front of a lithium ion White text and logo on a blue background that says AAAS graphic with text on electricity bills Scientific data plot. The earth is in the lower left, looking out in the directions of the constellations Virgo, Serpens and Hercules to distances beyond 5 billion light years. As this video progresses, the vantage point sweeps through 20 degrees towards the constellations Bootes and Corona Borealis. Each colored point represents a galaxy, which in turn is composed of 100 billion to 1 trillion stars. Gravity has clustered the galaxies into structures called the “cosmic web”, with dense clusters, filaments and voids. Photo of scientists with a graphic overlay with the text "top 10 science stories of 2021"