https://www.vice.com/en_us/article/n7ej9w/earths-life-nourishing-water-came-from-interstellar-space-scientists-find

Earth’s water originated in interstellar space more than five billion years ago, making it more ancient than the Sun, reports a new study that reveals fascinating insights about the evolution of water in budding star systems. The finding will inform efforts to find other water-hosting habitable planets. 

Astronomers captured an unprecedented glimpse of water vapor surrounding the baby star V883 Orionis, located some 1,300 light years from Earth, enabling them to measure the ratio of two key versions of water for the first time in a developing star system. The results revealed that the composition of water in the V883 Orionis system is very similar to water content in many bodies of our own solar system, a discovery that adds weight to the theory that much of Earth’s water is sourced from interstellar dust grains that existed before the birth of the Sun.