All Water On Earth Is Older Than Our Sun, Say Scientists

Our planet is a ocean world and we are water people. Precisely 70.8% of the surface area of Earth is oceans, which contain 97% of Earth’s water. About 55%-60% of our bodies consist of water.

Where did water originally come from? It probably first arrived here on asteroids and icy comets from the icy outer reaches of the solar system, but even if that’s true then that’s only the last piece of the jigsaw. Did it exist in space before the Sun was born?

Yes, says new research published today in Nature, which reveals that water has been found around a young star for the first time. Scientists found at least 1,200 times the amount of water in all Earth’s oceans around a protostar—a very young star in the early stages of its evolution—1,305 light-years distant in the constellation Orion.

This artist’s impression shows the planet-forming disc around the star V883 Orionis. In the outermost part of the disc water is frozen out as ice and therefore can’t be easily detected. An outburst of energy from the star heats the inner disc to a temperature where water is gaseous, enabling astronomers to detect it. The inset image shows the two kinds of water molecules studied in this disc: normal water, with one oxygen atom and two hydrogen atoms, and a heavier version where one hydrogen atom is replaced with deuterium, a heavy isotope of hydrogen.

It gives credence to the theory that water comes from the interstellar medium—the gaseous, dusty regions of space between stars. It indicates that water in our solar system formed billions of years before the Sun.

“Before now, we could link the Earth to comets, and protostars to the interstellar medium, but we couldn’t link protostars to comets,” said John Tobin, an astronomer at the National Science Foundation’s National Radio Astronomy Observatory (NRAO) and the lead author. “This is confirmation of the idea that the water in planetary systems formed billions of years ago, before the Sun, in interstellar space, and has been inherited by both comets and Earth, relatively unchanged.”

This chart shows the location of the young star V883 Orionis in the famous constellation of Orion. Most of the stars visible to the naked eye on a clear dark night are plotted. The location of V833 Orionis is marked with a red circle. This star is very faint and needs a large amateur telescope to be seen visually. It is very close in the sky, and physically associated with, the huge and brilliant Orion Nebula just to the north-west.

The new research essentially reveals the journey of water from star-forming gas clouds to planets. The water was found in the star’s circumstellar (or “planet-forming”) disc by the Atacama Large Millimeter/submillimeter Array (ALMA) radio observatory in Chile.

However, it was the unique status of the star that made this science possible. V883 Ori is a protostar just hot enough for the water around it to turn to gas much farther out that with most stars—and therefore more easily visible to radio telescopes. In most star systems water exists as ice, which is impossible for radio telescopes to detect.

“If the snow line is located too close to the star, there isn’t enough gaseous water to be easily detectable and the dusty disk may block out a lot of the water emission,” said Tobin. “But if the snow line is located further from the star, there is sufficient gaseous water to be detectable, and that’s the case with V883 Ori.”

Wishing you clear skies and wide eyes.