Free Astronomy Magazine September-October 2026

SEPTEMBER-OCTOBER 2026 T he Atacama Large Millimeter/ submillimeter Array at its 16,500 ft elevation site in northern Chile. Still under construction at the time of this photo, ALMA is today the most powerful telescope of its kind in the world, with 66 high-precision antennas, each 12 meters in diame- ter, spread over distances of up to 16 kilometres. [W. Garnier, ALMA (ESO/NAOJ/NRAO)] or CO, a molecule commonly used to trace molecular gas. The VLA de- tected a low-energy CO transition that traces relatively cool gas – the most distant detection of this kind ever reported, and the first in a star- forming galaxy this early in cosmic history. “Our results show galaxies just 700 million years after the Big Bang al- ready contained large reservoirs of cold gas available for star forma- tion,” said Cescon. “With these deep NSF VLA observations, we were able to overcome the observational chal- lenges posed by the cosmic mi- crowave background.” That background – the ancient glow of radiation left over from the early Universe – makes these observations especially challenging. At high red- shift, it is warmer and brighter than it is today, like trying to spot a faint light against an increasingly bright sky. By accounting for this effect, the team derived a molecular gas mass of roughly 100 billion solar masses, a figure independently supported I mage of the galaxy REBELS-25, taken by the Atacama Large Millimeter/submil- limeter Array (ALMA). [ALMA (ESO/NAOJ/NRAO)/L. Rowland et al.]