Between oceans, glaciers, polar ice caps, and lakes,
watery goodness covers almost 71% of Earth’s surface.
And that’s pretty special—Earth is the only one of the rocky planets in our solar system with this much water.
So when it comes to BIG questions, one of the biggest is where did Earth’s water originally come from?
One new study says maybe…the Sun?
But to get there, we gotta start a little further back.
For decades, planetary scientists and astrobiologists have been building two competing hypotheses
for just how Earth got so gosh dang WET.
Option one: Water was inside the Earth when it formed in the first place.
The idea goes that minerals in the mantle of our ancient, primordial Earth stored hydrogen and oxygen.
When those minerals melted in the natural course of geothermal activity,
the hydrogen and oxygen dissolved together in the magma as water.
When that magma got spewed out onto Earth’s surface via volcanoes, the water came too.
Alternatively, maybe those elements stored in Earth’s minerals were vaporized by an impact from some comet or asteroid…
possibly even the BIG impact we think created our moon!
Those vaporized elements combined and settled on the Earth’s surface, resulting in our life-giving liquid.
But option two is an answer that doesn’t come from so close to home.
Many scientists think that water was just chillin’ on comets, meteorites, asteroids, etc., out in space.
When these guys crashed into us…hey presto, water on Earth!
Where this gets a little sticky though, is the numbers.
Scientists have studied the remnants of asteroids and meteorites that crashed into us
wayyyyy back at our planet’s beginning.
These do contain certain kinds of hydrogen, what are called isotopes.
But the ratio of the hydrogen isotopes on these ancient astrophysical bodies
doesn’t match the ratio in our oceans today.
To get the right ratio, the water from these crashed objects would have needed to mix with another,
lighter isotope of hydrogen for us to get the kind of water we have today.
So, where’d that “different” water come from?
This is where we come back to the Sun.
It seems pretty bizarre that our WATER could have come from a giant ball of burning gas, but stay with me.
See, our Sun is constantly undergoing nuclear fusion.
That’s an incredibly energetic process that means its outermost atmospheric layer, the corona,
reaches over one million degrees Celsius.
This extreme heat flings particles out from the Sun’s surface, mostly protons and electrons,
creating streams of particles that can travel all throughout our solar system
at around 1.6 million kilometers per hour.
In 2021, a team analyzed minuscule grains of dust collected by the Hayabusa space probe
from a near-Earth asteroid called Itokawa.
They irradiated this dust with protons like those found in solar wind, and that process made water!
And this water fits the profile of what would have been needed to even out our hydrogen imbalance.
An asteroid like that could definitely have been the start to our waterworld oasis—
scientists’ calculations found that Itokawa may contain up to 20 liters of water for every cubic meter of rock.
So now the “space rocks crashing into Earth” option has another strong argument in its favor.
But the other contending hypothesis isn’t going down without a fight.
Because exciting new evidence from Mars indicates that the Red planet also had water right from the beginning,
meaning the “water was with us all long” hypothesis may apply to more than just Earth.
But whether water came from the outside in OR the inside out…
if either—or both—of those happened, that means there may be water on other rocky planets too
that are also a perfect distance from THEIR star.
And…well.
As we know, where there’s water, there’s life.
It's just another piece of the puzzle clicking into place, telling us that we are almost certainly not alone in our universe.
If you want more on perfect planetary candidates for extraterrestrial life, then check out this video here.
If you have questions about this work or want us to cover something similar, leave us a comment down below,
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As always, thanks for watching, and I’ll see ya next time.