智利沙漠中的射电望远镜，聆听宇宙初生的回响
Perched at 5,000 metres above sea level, the Atacama Desert's bone-dry air and near-total absence of radio interference create an ideal crucible for listening to the cosmic microwave background — faint whispers from the universe’s infancy that most earthly locations drown in static. Here, the Atacama Large Millimeter/submillimeter Array (ALMA), a constellation of 66 high-precision antennas, resolves distant galaxies and star-forming nurseries with a clarity that would be impossible beneath the thick, noisy atmosphere of lower altitudes.
By synchronising these dishes across baselines that extend up to sixteen kilometres, astronomers effectively synthesise a single telescope the size of a small city, capturing millimetre- and submillimetre-wavelength light that passes through cosmic dust unimpeded. This technique, known as interferometry, unveils the cold, obscured regions of space — the swirling discs of gas and dust around young stars, for instance — which visible-light telescopes simply cannot penetrate.
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