💧 Immense water reservoirs on the scale of the Universe?

An observation has just shaken up what was known about the origin of water on Earth. The SPHEREx space telescope, newly commissioned by NASA, has spotted huge reservoirs of water ice in Cygnus X, one of the most active star-forming regions in the Milky Way. These types of icy interstellar clouds could well be the source of the water in our oceans.

The images, taken in 2025 and recently published, show water ice in bright blue amid dark dust lanes where new stars are born. SPHEREx mapped these frozen materials across Cygnus X, a massive star-forming region filled with gas and dust. This detailed mapping offers an unprecedented look at the distribution of ices in our galaxy.


These ice reservoirs are made up of molecules like water, carbon dioxide, and carbon monoxide. These essential ingredients for the chemistry of life form on microscopic dust grains. According to scientists, these interstellar ices represent a major source of water in the universe, and could seed planetary systems. The water in Earth's oceans and that in comets would thus share a common origin.

Phil Korngut, a researcher at the California Institute of Technology, compares these regions to interstellar glaciers capable of delivering a massive water supply to new stellar systems.

The study confirms the idea that interstellar ice forms on dust grains smaller than smoke particles. Water ice is not uniformly distributed: it concentrates in the densest regions of cosmic dust, which act as shields against ultraviolet radiation from young stars. This protection allows fragile molecules to survive.

As SPHEREx continues its two-year all-sky survey, researchers are eager to build a detailed map of the distribution of water and other molecules like carbon dioxide in the Milky Way. They also want to understand how these ices respond to different levels of ultraviolet radiation. This mission is just beginning, according to NASA.

The results of this study were published in The Astrophysical Journal on April 15, 2025. They mark an important step in understanding the water cycle in the universe and its role in the emergence of life.