Free Astronomy Magazine September-October 2026

SEPTEMBER-OCTOBER 2026 REBELS-25 is observed at a cosmic distance so vast that its light has been stretched – or redshifted – by the expansion of the Universe to a redshift of z = 7.31. Astronomers see the galaxy as it was roughly 13 bil- lion years ago, during the Epoch of Reionization — the period when the first stars and galaxies were trans- forming the young Universe, just 5% of its current age. Galaxies grow by turning gas into stars, and molecular gas is the primary raw material for that process. Until now, astronomers had strong indirect evidence that some early, massive galaxies con- tained large gas supplies, but di- rectly detecting this material at such early cosmic times has been ex- tremely difficult. The team, led by Karin Cescon of Leiden University, used deep VLA observations to search for faint ra- dio emission from carbon monoxide, ALMA and VLA reveal vast reservoir of cool molecular gas in REBELS-25 by ALMA Observatory Nicolás Lira, Jill Malusky, Bárbara Ferreira A stronomers have directly de- tected a vast reservoir of cool molecular gas in REBELS-25, a massive star-forming galaxy seen just 700 million years after the Big Bang. The discovery, made using the NSF Very Large Array (VLA) and the Atacama Large Millimeter/submil- limeter Array (ALMA), provides a rare direct measurement of the star- forming fuel available to a galaxy in the early Universe.