Five Great Enigmas of Earth | Explore Universe
Universe | We have been studying it for thousands of years and yet how far we are to know it! Many of the things that are related to it are lingering mysterious.
With our advanced technology – with which we look at the Earth in small details hundreds of kilometres away, we go right to the moon to study it on the spot, measure infinitesimal things of small, colossal times, large – the hope to uncover his secrets. And if many of our hopes of knowing it has been fulfilled – which entitles us to hope and to continue to explore – there are still many things that, even in the 21st century, escape our understanding and remain stones in science, so advanced as they are today. Here are 5 of the “enigmas” of the Earth – unexplained features, completely unsolved aspects, for which we have, for the time being, only assumptions, not certainties.
The earth was formed 4.54 billion years ago, according to the calculations of scientists, who came to this conclusion by analyzing the oldest terrestrial rocks they could find, as well as the oldest meteorites fallen on Earth (starting from the idea that Earth and meteorites formed at the same time when the Solar System was formed by aggregating solid matter around the Sun.) Since then, the planet itself – its internal structure, its atmosphere and its most striking feature, life – as well as the heavenly bodies in her orbit, have gone through countless changes. And some aspects of this evolution have remained unknown to us today.
Where Did the Water Come From?
Some scientists believe that when it formed, Earth was a dry, dry planet, with no water in its structure.
How has the richness of today’s water that sustains the life of the planet? The amount of water has increased, of course, gradually over time – and there are several factors that could have contributed to this “enrichment” in the water – but how was it at first? Because there is not enough geological evidence dating from this early period, we do not know exactly how the Earth got its water. A hypothesis has been developed at one point that water came from space, brought by comets (mostly formed of ice), but further specific and detailed analyzes – the measurement of the proportion of hydrogen isotopes in the ocean’s ocean and in the comets’ ice – have yielded results that contradict this hypothesis: comet water is not the same as on Earth.
A new hypothesis puts forward another category of spatial objects, the carbonaceous chondrites (one of the types of meteorites that can be found on Earth), suggesting that, unlike the scientific belief mentioned at the beginning, Earth would be ” born “with some water in it. Do not water as we see it today in rivers and lakes, but water molecules that were part of the solid matter composed of the fragments of matter which, by aggregation, formed the Earth. The analyzes of the seleniferous rocks, the carbonaceous chondrites and the rocks on Earth show that the water of these 3 types of materials has a common origin. The discovery supports a recent and original theory that once the giant Jupiter, the fifth planet from the Sun (and the largest of the Solar System), would have moved a bit from its place, that is, at some point , at the beginning of the formation of the Solar System, would have temporarily changed its orbit. This “migration” would destabilize the orbits of space objects in the asteroid belt, between Mars or Jupiter’s orbit. The space rocks in this region would have been pushed into the Solar System, and some of them, rich in water, would have come to the Earth. Is a particularly interesting vision, still too new to be fully accepted and still to be verified, and will be confirmed or denied further studies.
Universe | Where is the Xenon?
Earth’s atmosphere consists of a mixture of gases: nitrogen is predominant (78.09%), there is a significant amount of oxygen (20.95%), then carbon dioxide (0.035-0.039%) and various other gases.among these “other gases” are so-called rare gases, noble gases or inert gases, so called because they have very low chemical reactivity, do not form chemical combinations with other substances.rare gases are found in the atmosphere in different proportions, the most abundant being argon (0.93% – much more abundant than carbon dioxide); the other rare gases are helium, neon, krypton, radon and xenon.
For a long time, scientists have noticed a problem with xenon: its concentration in the Earth’s atmosphere is 90% lower than expected, according to calculations.
A very recent hypothesis published by scientists at Jilin University in Changchun, China, suggests that xenon would be hidden in the nucleus of the planet, being chemically combined with the iron and nickel of which the Earth’s “core” is mostly composed. With all its low reactivity, xenon could under certain special conditions of pressure and temperature react chemically with other elements. The calculations and experiments of Chinese researchers show that, at the huge temperatures and pressures in the core of the Earth, xenon could react with both iron and nickel; the most stable of the molecules formed would consist of a xenon atom and 3 iron atoms – XeFe3 – or a xenon and nickel-XeNi3 atom.
But, in fact, what is the nucleus?
The fact that we know that the xenon that is missing from the planet’s atmosphere is hidden in the nucleus does not, however, or at all, elucidate all the mysteries of this nucleus. It is understood that no one has arrived there to see what things are on the scene, so everything we know has been deduced from the results of many measurements of the density of the planet, its magnetism, and other specific features analyzed with sophisticated techniques, as well from the results of experiments that recreate the harsh pressures and temperatures in the core of the Earth.
As strange as it sounds, the core is composed, it is believed, in two layers: an “inner core” and an “outer core”. The internal one would be solid – or, in any case, behave like a solid – with a radius of approx. 1220 km and a temperature of approx. 5430 degrees Celsius. The outer core would be a liquid, melted, 2266-kilometer thick, with temperatures between 4400 and 6100 degrees Celsius.
It is believed that both internal and external core is made up of an iron and nickel alloy (ie a physical “mixture” of the two metals, not a chemical combination at the molecular level); in the outer nucleus would still be found, say the authors of a study published in 2011, other elements, such as oxygen and sulfur. The recent hypothesis outlined above – that xenon, and in chemical combinations of iron and nickel, is present in the structure of the Earth’s nucleus, shows how far we are still to know everything about the hot core of the Earth. And we are just as far and aware of everything about the magnetic field of the Earth that is generated by this core and which, among other characteristics, has one to reverse its polarity from time to time – a dynamic on which scientists have not yet deciphered.
How Did the Moon Form?
There is no consensus among scholars as to how the Earth’s natural satellite was formed. The gigantic impact theory says that in the early days of our planet, about 4.5 billion years ago, it was hit by another celestial body, about the size of Mars; of the material thrown into space by this impact would have lengthened the Moon. Although it is currently the most widely accepted of the scenarios that attempt to explain the formation of the Moon (and is supported by the similarities between the Moon and the Earth, suggesting that these two celestial bodies would have a common origin), the gigantic impact theory has some weaknesses that prevent it from accepting it unanimously; for example, an impact of this magnitude would have left some geological traces that have not been identified in the Earth’s crust structure.
Another interesting idea related to the formation of the moon: some scientists believe that initially the Earth would have had two moons (formed by the impact described above) and the smallest entered at a time in a slow collision with its sister bigger than two moons, forming one, the one we know today. The hypothesis would explain why the two “faces” of the Moon are so different between them: the visible part of the Earth is flat and full of craters, while the hidden side has a much sharper relief with mountain ranges up to 3,000 m altitude.
In addition to the gigantic impact theory, a number of alternative theories are circulated in the scientific world.
The theory of fission, which states that the Moon would be a piece of earth bark and mantle as a result of the centrifugal force generated by a very rapid rotation of the Earth. The binary image of the motif, which claims that Moon and Terra were born at the same time in the same a region of space, from the material that clustered into two distinct spatial bodies – Earth and its natural satellite. A new alternative theory is that of capturing the Moon – its attraction by Earth in its gravitational field.
In connection with this latest scenario, a very recent proposal suggests an “extraterrestrial” origin of the Earth’s natural satellite: The moon would be a “gift” from Venus, the planet’s neighbour and “sister” of the Earth.
Venus would have once had a natural satellite that he lost; captured by the terrestrial gravitational field, this celestial body has become the Earth’s natural satellite.
All the scenarios proposed so far are plausible to a certain extent, but none can fully explain how the Earth has acquired its natural satellite. So the Moon still retains its mystery.
How Many Moons Has the Earth?
As if the difficulty of understanding how the Moon arose would not have been enough, scientists have begun to wonder, more recently, if our planet even has a single “moon” or has more.
Astronomers have recently become more preoccupied with so-called Temporary Captured Objects (TCOs), small asteroids that our planet, because of the gravitational pull it exerts, cling to them from time to time, attracting them in her gravitational field and fixing them in orbit for a certain amount of time. Most of these space objects remain in orbit between 6 and 18 months, then escape from the gravitational field of the Earth and are lost in space. But others and others always arrive instead of the lost ones. The simulations show that it is likely that at any moment around the Earth orbit two asteroids of the size of a washing machine and some other six smaller ones (with a diameter of approx.half a meter), captured by our planet from alien space. Occasionally, about 50 years later, a larger asteroid arrives, the size of a truck.
Scientists are very interested in these mini-moons: such rocks, which have not been affected by atmospheric phenomena on Earth and have not come into contact with terrestrial soil, could provide a wealth of new and interesting data on how the Solar System was formed. Companies that develop space resource exploitation technologies are interested in these mini-months: although many are too small to be profitable, it could still be useful to test them for asteroid-mining technologies – an activity that, although it still sounds “SF,” could become reality in only a few decades.
There are still many “big enigmas” related to our planet, its formation and evolution.even without counting the “supreme enigma” – as life appeared on Earth -, the planet is full of secrets. Last year scientists announced the discovery of a new continent! Yes, a micro-continent, unknown until then – it’s right, not visible to the surface of the ocean, like others, but hidden deep under the colossal lava masses. Under the islands of Reunion and Mauritius in the Indian Ocean, the continental fragment, called Mauritius, broke out of the southern continental block, Gondwana, 60 million years ago.
And the study announcing its discovery, published in Nature Geoscience, suggests that such micro-continents could be larger in numbers than thought.
Here is a whole new field of research; who knows how many other such micro-continents are hiding under the ancient rocks that have not yet been discovered, and what new and amazing things we will learn in the near future from scholars who are trying to decipher the mysteries of our mysterious planet.
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