Free Astronomy Magazine May-June 2026

MAY-JUNE 2026 A bove: This image shows the complex distribution of molecular gas in the Central Molecular Zone (CMZ) of the Milky Way. It was obtained with the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner. This map is as long as three full Moons side-by-side in the sky, and it is in fact the largest ALMA image ever obtained. This map is part of ACES — the ALMA CMZ Exploration Survey — a project designed to understand how gas condenses into stars in the extreme and chaotic environment at the heart of our galaxy. The survey has charted the distribution of dozens of different molecules, five of which are shown here in different colours: sulphur monoxide (cyan), silicon monoxide (green), isocyanic acid (red), cyanoacetylene (blue), and carbon monosulphide (magenta). The stars in the foreground of this image were observed at in- frared wavelengths (Y, Z and J filters) with ESO’s VISTA telescope as part of a different project. The actual density of stars in the CMZ is much higher than what is shown here, where we have opted to highlight the details in the molecular cloud. Note that the edges of the ALMA map appear somewhat sharp because the ALMA observations do not cover the entire rectangular area here. [ALMA(ESO/NAOJ/NRAO)/S. Longmore et al. Background: ESO/D. Minniti et al.] T his image shows the location of the Central Molecular Zone (CMZ), a region at the core of our galaxy rich in dense and intricate gas clouds. This zone has been mapped with the Atacama Large Millimeter/submillimeter Array (ALMA), as part of the ALMA CMZ Exploration Survey or ACES. The inset is an ACES image where different molecules are displayed in dif- ferent colours. The entire image – the largest ever made with ALMA – is as long as three full Moons side-by-side in the sky. [ALMA(ESO/ NAOJ/NRAO)/S. Longmore et al. Stars in inset: ESO/D. Minniti et al. Milky Way: ESO/S. Guisard]