- 3517 - EARTH - many mysteries to work on? The biggest mystery for me is how on Earth could I even be here writing this? We have been trying to figure our earth for a long time. The first Earth Day was held in 1970, geologists were still putting the finishing touches on plate tectonics, the model that explains how the Earth's surface takes shape.
--------------------- 3517 - EARTH - many mysteries to work on.
- More than 50 years later many riddles still remain when it comes to our planet. Here are some of Earth's biggest unsolved mysteries in 2022 :
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- Why is the Earth wet? Scientists think Earth was a dry rock after it coalesced 4.5 billion years ago. So where did this essential chemical, H2O, come from?
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- Perhaps an interstellar delivery system, in the form of massive impacts about 4 billion years ago. Pummeled by icy asteroids, the Earth could have replenished its water reservoirs during the period, the “Late Heavy Bombardment“. But the beginnings of Earth's water are shrouded in mystery because so little rock evidence remains from this time period.
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- Another mystery is “What's down there in the core“? The xenon gas missing from Earth's atmosphere might have been found. Scientists say it is stuck in Earth's core, where the noble gas is bound with other atoms.
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- For a while, the composition of Earth's unreachable core was a solved mystery … at least in the 1940s. With meteorites as proxy, scientists gauged the planet's original balance of essential minerals, and noted which were missing. The iron and nickel absent in Earth's crust must be in the core, they surmised.
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- But gravity measurements in the 1950s revealed those estimates were incorrect. The core was too light. Today, researchers continue to guess at which elements account for the density deficit beneath our feet. They're also puzzled by the periodic reversals in Earth's magnetic field, which is generated by the outer core's flowing liquid iron.
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- 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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- Year 2022 computer simulations suggest that Earth's hot and highly pressurized inner core could exist in a "superionic state". It could be 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 superionic state under the inner core conditions, showing high diffusion coefficients like a liquid This suggests that the inner core can be in a superionic state rather than a normal solid state.
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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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- 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, but even today the picture is far from clear.
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- A 2021 study of how a type of seismic wave called a “shear wave” moved through our planet's interior revealing 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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- Accessing the core by probe is impossible, so the researchers turned instead to a simulation compiling seismic data and feeding it into an advanced computer program 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. This is a framework of iron atoms around which the other elements, driven by powerful convection currents, are able to freely swim.
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- If the simulation lines up with reality, 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, and science hopes to constrain some of the key parameters determining geophysical models of the inner core.
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- One of the theories suggests that a titanic collision between the Earth and a Mars-size protoplanet formed the moon. There's no universal consensus on this “giant impactor theory“. The chemical composition of both rocky bodies matches so closely it suggests the moon was born from Earth, not a separate impactor.
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- A fast-spinning young Earth could have flung off enough molten rock during impact to form a chemically similar moon.
- Once Earth formed and cooled where did life come from? Did it start n the ocean in hydrothermal vents? Alkaline hydrothermal vents are suggested to be the birthplace of the first living organisms on the ancient Earth.
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- Or was life brewed on Earth or sparked in interstellar space and delivered here on meteorites? The most basic life components, such as amino acids and vitamins, have been found on ice grains inside asteroids and in the most extreme environments on Earth.
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- Figuring out how these parts combined to form the first life is one of biology's biggest hurdles. No direct fossil traces of Earth's first inhabitants, which were probably primitive, rock-chewing bacteria, have yet been found.
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- Where did all the oxygen come from? Do we owe our existence to “cyan bacteria“, microscopic creatures that helped to radically transform Earth's atmosphere. They pumped out oxygen as waste, and filled the skies with oxygen for the first time about 2.4 billion years ago.
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- Rocks reveal oxygen levels cruised up and down like a roller coaster for 3 billion years, until they stabilized around the Cambrian Period about 541 million years ago. Did bacteria spike the air, or was there another contributing factor? Understanding the shift to an oxygen-rich Earth is a key factor in decoding the history of life on our planet.
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- What caused the Cambrian explosion? Arthropods from the Burgess shale, such as the trilobite Olenoides and a chelicerate called Sidneyia, exploded in morphological diversity following the so-called Cambrian Explosion.
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- The appearance of this complex life in the Cambrian, after 4 billion years of Earth history, marks a unique turning point. Suddenly there were animals with brains and blood vessels, eyes and hearts, all evolving more quickly than during any other planetary era known today.
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- A jump in oxygen levels just before this Cambrian explosion has been offered as explanation, but other factors could explain the mysterious rise of the animals, such as the arms race between predator and prey.
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- When did plate tectonics start? Thin plates of hardened crust knocking about Earth's surface make for beautiful mountain sunsets and violent volcanic eruptions. Yet geologists still don't know when the plate tectonics engine revved up.
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- Most of the evidence has been destroyed. Just a handful of tiny mineral grains called “zircons” survive from 4.4 billion years ago, and they tell scientists the first continental-like rocks already existed. The evidence for early plate tectonics is controversial. And geologists still wonder how continental crust forms.
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- Geologists predicted an earthquake at Parkfield, Calif., by 1994, and set up instruments to catch the coming temblor. The actual quake hit in 2004. One of the biggest hurdles is that geologists still don't understand why earthquakes start and stop. But there have been advances in predicting aftershocks and manmade earthquakes, such as those linked to wastewater injection wells as used in fracking.
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- Mother Earth still gives us many mysteries to work on. Fracking and all.
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March 25, 2022 EARTH - many mysteries to work on. 3517
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