Overview

• Eos, one of the largest molecular clouds ever observed, spans 40 full Moons in the sky and has a mass approximately 3,400 times that of the Sun.
• The cloud remained undetected until researchers applied a novel far-ultraviolet fluorescence technique to data from the STSAT-1 satellite, bypassing traditional CO-based detection methods.
• Situated on the edge of the Local Bubble, Eos provides a nearby laboratory to study molecular cloud formation, dissociation, and the processes that lead to star and planet creation.
• Researchers estimate that Eos will dissipate in roughly six million years, offering a limited window to study its evolution and role in the interstellar medium.
• The discovery, published in *Nature Astronomy*, paves the way for further searches for hidden molecular clouds and could transform our understanding of galactic gas reservoirs.