- 3551 - EARTH - core first, water next? What if you could dig a hole all the way to the center of the earth? What would you find down deep? The planet's core could be a mushy mix of solid and liquid. For sure the Earth's core is weirder than science first thought.
--------------------- 3551 - EARTH - core first, water next?
- Earth's inner core may be filled with a weird substance that is neither solid nor liquid. For more than half a century, scientists believed that Earth's deepest recesses consist of a molten outer core surrounding a densely compressed ball of solid iron alloy.
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- New research, February, 2022, offers a rare insight into the inner structure of the planet and it's far weirder than previously thought. Earth's hot and highly pressurized inner core could exist in a "superionic state". This is a whirling mix of hydrogen, oxygen and carbon molecules, continuously sloshing through a grid-like lattice of iron.
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- Hydrogen, oxygen and carbon in hexagonal close-packed iron transform to a super-ionic state under the inner core conditions, This superionic state shows high diffusion coefficients like a liquid.
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- The planet's core is subject to bone-crushing pressures and scorching temperatures as hot as the surface of the sun, and its contents have long been a subject of speculation among scientists and science fiction authors alike.
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- Since the 1950s, advances in the study of earthquake-generated seismic waves which travel through the core have enabled researchers to make more refined guesses as to what's inside the heart of the planet.
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- A 2021 study of how a type of seismic wave called a shear (or "s") wave moved through our planet's interior revealed that Earth's inner core isn't solid iron, as was once believed, but is instead composed of various states of a "mushy" material consisting of an iron alloy of iron atoms and lighter elements, such as oxygen or carbon.
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- Computer simulations were designed to recreate the effects of the core's extreme pressures and temperatures on an assortment of likely core elements: such as iron, hydrogen, oxygen and carbon.
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- In a regular solid, atoms arrange themselves into repeating grids, but the core simulations suggest instead that in Earth's core, atoms would be transformed into a superionic alloy, a framework of iron atoms around which the other elements, driven by powerful convection currents, are able to freely swim.
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- The solidification of iron at the inner core boundary does not change the mobility of these light elements, and the convection of light elements is continuous in the inner core.
The constant swilling of the mushy superionic materials could help to explain why the inner core's structure seems to change so much over time, and even how the powerful convection currents responsible for creating Earth's magnetic field are generated.
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- Global seismology is making progress, with more seismological probes becoming rapidly available. They hope to constrain some of the key parameters determining geophysical models of the inner core.
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- Other simulations being researched are to understand where did Earth’s water come from? That’s one of the most compelling questions in the ongoing effort to understand life’s emergence.
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- Earth’s inner solar system location was too hot for water to condense onto the primordial Earth. The prevailing view is that asteroids and comets brought water to Earth from regions of the Solar System beyond the frost line.
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- Most of the hydrogen was already here, waiting for Earth to form. To understand the origin of Earth’s water, scientists study its isotopic compositions. Not only Earth’s water but also the evidence of water in meteorites, asteroids, and anywhere else in the Solar System they find it.
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- Scientists have known about “isotopes” since the early 20th century. There are three naturally occurring isotopes of hydrogen: 1H, 2H, and 3H.
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- 1H and 2H are stable, while 3H is unstable. The three hydrogen isotopes are also called protium, deuterium, and tritium. Water contains different amounts of the three, especially protium and deuterium. Scientists express these relative amounts as a ratio. The D/H ratio is the ratio of deuterium to hydrogen. Researchers often use the terms 1H, protium, and hydrogen interchangeably.
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- Deuterium can take the place of hydrogen in the water molecule. When deuterium takes hydrogen’s place in a quantity of water, it’s called “heavy water“. Earth water only occasionally contains H2O molecules with deuterium rather than hydrogen.
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- We know the D/H ratio of water on Earth to an exact degree.
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-------------------------- 1.5576 ± 0.0005) * 10^-4.
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- The ratio is a fingerprint scientists use to compare Earth’s water with water reservoirs elsewhere in the Solar System. For example, hydrogen contained in minerals inside ancient meteors, though it’s not water, can have different hydrogen isotope ratios that reflect the D/H present when the minerals form.
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- Back to when the Sun was born in a molecular cloud. After the Sun took shape in that cloud, it was surrounded by a smaller collection of gas called a “solar nebula“. The planets formed from the material in the solar nebula.
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- This new study focuses on the 200,000 years after the Sun formed, but before any planetary embryos formed. To understand that time period, the researchers examined “calcium-aluminum-rich inclusions” (CAI) in a type of meteorite called “carbonaceous chondrites“.
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- CAIs are the oldest rocks we have. The minerals inside them are some of the first solids to condense out of the protoplanetary disk. They’re 4,567.30 ± 0.16 million years old. CAIs define the Solar System’s age because they date back to the primordial Solar System before planets formed.
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- All primary minerals formed by condensation from the solar gas turned out to have low hydrogen content and also to be depleted in deuterium with the end member composition being similar to that expected for the main solar nebular gas.
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- CAIs with minerals containing water records with two separate isotopic fingerprints:
--------------------- The first type matches the D/H ratio of the solar nebula,
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---------------------- The second type more closely resembles the D/H of Earth’s water.
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- The early existence of a gas with Earth-like isotopic composition implies that Earth’s water was there before the accretion of the first constituent blocks of our planet. It presents evidence that the well-accepted idea of how Earth’s water got here may not be as solid as thought. It’s the same with our understanding of how planets form.
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- At least a significant portion of Earth’s water was here early in the planet’s life, rather than delivered later by comets and icy planetesimals.
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April 21, 2022 EARTH - core first, water next? 3551
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