This is scientific American 62nd science. I'm Julia Rosen. Got a minute?

Water. Earth has loads of H2O, but did it always?

This question has plagued scientists for decades.

Conventional wisdom has it that the Earth formed without any water.

Then meteorites carrying water smashed into the planet

dumping their precious cargo.

But now a team of geologist has challenged this idea.

They say water may have been here from the start.

The scientists discovered that the chemical signature of water on Earth

matches the signature of water in an ancient group of asteroids called Euchrites.

These bodies form just a few million years after the birth of the solar system.

And because Earth and Ukraine seem to share the same source of water,

the reasoning goes, Earth must have gotten its water around the same time the

eukrites did, which has big implications.

Because Earth got its water early,

really the whole inner solar system got its water early

means that planets once they fully formed

and got cool enough that water would be stable on the surface, they could be habitable.

The Woods Hall oceanographic institutions Adam Serafian, who led the research.

It wasn't like these planets are just

waiting around, waiting for the water, life's ready to go,

we just need water here.

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