Direct evidence: extended rotation curves of spiral galaxies

Radio astronomy, particularly through the use of large single-dish telescopes and interferometers, has revolutionized our understanding of galactic and extragalactic phenomena. By 1970, advancements in telescope size, precision, and receiver technology enabled finer mapping of radio sources, including galaxies, at unprecedented distances. The Jodrell Bank Observatory's 250-foot telescope, among others, played a pivotal role in this progress. These developments allowed astronomers to detect fainter signals more efficiently, significantly expanding our ability to study the universe. Additionally, the advent of radio interferometers, which combine signals from an array of antennae, offered a means to achieve even higher resolution without the engineering limitations of larger single-dish telescopes.

(Ed.). (2010). Direct evidence: extended rotation curves of spiral galaxies. The Dark Matter Problem, 38–56. https://doi.org/10.1017/cbo9781139192309.004