Water is essential for life, but when did it first appear in the universe?
A new study suggests that water may have formed much earlier than scientists previously thought—as soon as 100 to 200 million years after the Big Bang.
This finding, published in Nature Astronomy, could mean that water was already present when the first galaxies formed.
How did water form so early?
Water is made of hydrogen and oxygen. Hydrogen was created during the Big Bang, but oxygen comes from stars—formed in nuclear reactions inside them or released in powerful supernova explosions.
Scientists weren’t sure when the first water molecules appeared because they needed oxygen from early stars.
To investigate, researcher Daniel Whalen and his team used computer models to simulate two supernovae—massive star explosions.
One star was 13 times the mass of the Sun, and the other was 200 times the Sun’s mass.
Their models showed that these explosions created large amounts of oxygen—enough to potentially form water.
How much water was produced?
After the supernova explosions, the newly formed oxygen mixed with surrounding hydrogen and began forming water. The team found that:
- In the smaller supernova, tiny amounts of water formed 30 to 90 million years later.
- In the larger supernova, much more water—about 0.001 times the Sun’s mass—formed in just 3 million years.
These dense regions of gas where water formed could have become sites for new stars and planets to take shape.
What does this mean?
If water could survive the formation of the first galaxies, it may have played a role in the early development of planets—billions of years ago.
This challenges previous ideas about when water first appeared in the universe and suggests it could have been present in the very first planetary systems.
This exciting discovery shows that water—and possibly even the building blocks for life—may have been around much earlier than we thought.
