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Loading contentA direct, geometric distance measured from water masers orbiting in the accretion disc around a galaxy's central black hole. By tracking their motion and acceleration, the physical size of the disc is found and compared with its angular size — a one-step distance that anchors the ladder without relying on standard candles.
Facts on this topic will be cited from these primary and reference sources.
Mission data, planetary science, space telescopes, and public-domain imagery.
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