Free Astronomy Magazine January-February 2025

A mong the many views of the Universe that modern tele- scopes offer, some of the most breathtaking are images like this. Dotted with countless galaxies — each one of incomprehensible size — they make apparent the tremendous scale and richness of the cosmos. Taking center stage here, beguiling in its seeming sim- plicity, the elliptical galaxy NGC 1270 radiates an ethereal glow into the surrounding darkness. And although it may seem like an island adrift in the deep ocean of space, this object is part of something much larger than itself. NGC 1270 is just one member of the Perseus Cluster, a group of thou- sands of galaxies that lies around 240 million light-years from Earth in the constellation Perseus. This image, taken with the Gemini Multi-Object Spectrograph (GMOS) on the Gemini North telescope, one half of the International Gemini Ob- servatory — supported in part by the U.S. National Science Foundation and operated by NSF NOIRLab — captures a dazzling collection of galaxies in the central region of this enormous cluster. Looking at such a diverse array, shown here in spectacular clarity, it’s astonishing to think that when NGC 1270 was first discovered in 1863 it was not widely accepted that other galaxies even existed. Many of the objects that are now known to be galaxies were initially described as nebulae, owing to their cloudy, amorphous appearance. The idea that they are entities of a similar size to our own Milky Way, or ‘island Universes’ as Immanuel Kant called them, was speculated on by several astronomers throughout history, but was not proven. Instead, many thought they were smaller objects on the outskirts of the Milky Way, which many believed to comprise most or all of the Universe. 17 [International Gemini Observatory/NOIRLab/NSF/AURA − Image Process- ing: J. Miller & M. Rodriguez (International Gemini Observatory/NSF NOIRLab), T.A. Rector (University of Alaska Anchorage/NSF NOIRLab), M. Zamani (NSF NOIRLab) − Ack.: PI: Jisu Kang (Seoul National University)]