According to a new study published in Science, 30 to 50 percent of water on Earth is “primordial water,” meaning its molecules were created more than 4.5 billion years ago. That makes them older than Earth, the solar system, and even the sun. Scientists contend that the chemical signature of the primordial water could only have formed before the birth of planets, moons, comets, and asteroids. “It’s pretty amazing that a significant fraction of water on Earth predates the sun and the solar system,” said study leader Ilse Cleeves, an astronomer at the University of Michigan. The scientists still aren’t sure how the water arrived here, but some experts believe it came from ice in comets and asteroids that collided with a once-dry Earth.