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The Moon’s Birth May Have Given Earth Ingredients for Life | SciShow News


[ ♪ Intro ] When you look at Earth today, it’s easy
to imagine that it formed as a perfect, fertile planet, full of everything it needed to support
life. It’s a beautiful, big, wet rock. But scientists are pretty confident that’s
not what happened. They’ve known for a long time that, because
of Earth’s early conditions, the key ingredients of life, elements like carbon and nitrogen, have not been here since the beginning. Popular hypotheses suggest they arrived via
meteorites or comets, but none of those models totally checks out. So now, there’s another idea. Last Wednesday, in a paper published in Science
Advances, researchers announced that these elements most likely made a more dramatic arrival. Instead of coming on meteorites, they may
have come from a massive collision. The same massive collision that formed the
Moon. Now it’s not surprising that these elements,
called volatiles, came from elsewhere. They have really low boiling points, so when
Earth was forming, it would have been way too hot to hold onto them. And also, thanks to their chemistry, any volatiles
that didn’t escape would likely have been pulled into the Earth’s iron core. So, somehow, they must have been added to
the mix later. Otherwise, we wouldn’t be here. It’s just that figuring out that “somehow”
is much easier said than done. Like, even though the idea about Earth getting
its volatiles from meteorites is popular, the numbers have never quite added up. Earth’s ratio of carbon to nitrogen is way
higher than that of any meteorite. So in this new study, a team of researchers
at Rice University got creative to try and understand what happened. In their lab, they used machinery to put rocks
under extremely high pressure and temperature, squeezing them as if they were around 100
kilometers below the Earth’s surface. They were trying to recreate the environment that would have existed when planets’ cores were forming. And they found something interesting. In their experiments, a planet with an iron
core would normally pull in all the volatiles, just like on Earth. But if that core was rich with sulfur, the
volatiles were less attracted to it, so they remained free. That doesn’t mean much for Earth itself,
since our planet doesn’t have a sulfur-rich core. But it does mean that a foreign rock with
a core like that could have had plenty of volatiles in its outer layers. So if an object like this collided with Earth
at some point, it could have contaminated our planet with those elements that earth had long ago lost. You might be thinking that sounds like a lot
of sketchy “could have”s, but the researchers found that it was surprisingly likely. They ran around a billion simulations of the
evolution of the solar system, and found that the best explanation for the number and ratio of volatile elements on Earth is a scenario where an object around the size of Mars collides
with our planet. Now as for the timeline, in the best-fit scenario, the collision lined up with the one that formed the Moon. It’s a promising, and really convenient,
idea, but the case isn’t closed yet. This study mainly looked at the chemistry
that might have happened during a collision, but we’ll need to learn more about the physical
side of how planets grow and evolve. Still, if proven, this research backs up the
idea that, in all likelihood, we owe our whole existence to the colliding worlds of the early solar system. Of course, it’s not easy to decode the solar system’s history billions of years after events took place. Fortunately, some clues are locked away at
the edge of our solar system, and scientists are starting to uncover them. On Monday, in the journal Nature Astronomy,
researchers announced that they may have indirectly detected a kilometer-sized rock in the Kuiper
belt, the ring of icy objects past Neptune. If true, it would be the first time astronomers made a detection of an object like this on two separate telescopes, making it the most
convincing detection yet. These barren rocks might not seem like they
have much to do with us, but they’re kind of like long-lost relatives. Earth and the other planets formed from objects
like those. The difference is that this icy fringe of
the solar system wasn’t dense enough to form planets, so it’s barely evolved at
all in the last 4.6 billion years. So in the absence of time travel, it’s the
closest we can get to seeing what things were like when the planets were first forming. In the study, scientists were especially interested
in finding objects between one and 10 kilometers across, because rocks like these formed the
seeds of our planets. Unfortunately, objects that size are way faint. Like, much fainter than Pluto, so even the
largest telescopes can’t see them directly. But, in theory, and maybe now for the first
time in practice, we can detect them indirectly by measuring blips in the light as they pass
in front of stars. It’s a method called a stellar occultation. And it’s not easy to pull off. That blip in light is very small and lasts
less than a second, and with just one telescope, it can be embarrassingly difficult to tell
between a 4.6-billion-year-old space rock and, like, a bird that flew past. So the team in this study set up two identical
telescopes on the roof of a school in Japan, and monitored around 2000 stars for just over
a year. After sifting through more than 100,000 hours
of data, they found what they were looking for: one possible detection of a Kuiper belt
object passing in front of a star. So far, it’s just a candidate. Even though the chances are really small,
we can’t entirely rule out the possibility that the signal came from a statistical fluke,
or something like an asteroid. But if it is real, this tiny shadow can still
offer some insight. Making some assumptions about its shape and position, scientists peg its diameter at around 1.3 kilometers. That supports previous results that suggest
there may be more small objects in the Kuiper belt than some studies previously thought. And the better we understand how they’re
distributed, the better we can understand what kinds of objects grew into the planets and which ones stayed behind. To get closer to that answer, the team and
their collaborators plan to keep looking for other occultations that can tell us more about
these ancient rocks and the history we share with them. So, between our observations and simulations, we can start to fill in some of the holes in our solar system’s majestic history. Thanks for watching this episode of SciShow
Space News! And especially thank you to all the people
who support us on Patreon, helping us unpack science news like this. We love doing what we do and we’re very
thankful to have you on board. If you want to support the show and partner
up with a bunch of other curious, wonderful people, you can go to patreon.com/scishow. [ ♪ Outro ]

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