Recently read that water is older than the sun.How can we determine the age of water if it’s continuously being used in the water cycle?
In: Physics
To answer your question very specifically –
Water is made of hydrogen and oxygen atoms that have bound up together in a molecule, that bit is pretty easy.
Whatever process that is responsible for *making* the atoms come together and make the water, we’ve observed something fairly simple – every now and then something screws up and the oxygen picks up an extra particle called a ~~proton~~ neutron and this new water is obviously a teeeeny bit heavier than normal water so we call it *heavy water* or “deuterium”.
Anywho, we know from science how often heavy water forms during normal water production and what causes more of it to be made, or less of it.
By extension we know that the conditions that exist in deep space, specifically *not* conditions that exist on Earth, create higher than normal amounts of deuterium.
Long story short when we look at Earth’s water there *is too much deuterium*. So where does it come from? That’s an open theory but the article you read proposed it was water that was delivered to the Earth, pre-made in deep space. So things like asteroids and meteors and rocks from deep space had water than came to our baby solar system and got pulled into the Earth when it formed. Thus, the water is *older* than the Sun because it was made in deep space and then got sucked in the Earth after the Sun was born.
EDIT – Meant Neutron. Stupid sexy subatomic particles.
Pretty sure “older than the sun” refers to the H2O molecules, not oceans. And the water cycle doesnt break those molecules
They probably mean that they think there was water on Earth before the sun was “the sun”, which might mean before it got big enough for spontaneous fusion to occur. So it’s a statement of when they think the first space rocks with significant water on them either formed the Earth or crashed into it.
It’s like when people try to blow your mind by saying that your nipples are older than your teeth. They can’t precisely date either of them, it’s based on knowing what order past events happened in.
You can’t tell how old particular water is, because all the water gets mixed together, and you get new water molecules all the time from biological processes. There aren’t really any isotopes you can use because it’s all hydrogen and oxygen, and none of the radioactive ones live long enough to date back 4 billion years.
As I recall, this hypothesis is derived more from the suspected origins of water on Earth. Many suspect water came from one or more icy meteors impacting Earth. Earth has had water for a long time in its life, and any meteor impacts delivering that water would need to have travelled vast distances and thus would have to have been formed very long ago.
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