6 Things We Still Don't Know About Earth
Miscellaneous / / March 12, 2022
What color were the ancestors of plants, why there are skyquakes and where the Mediterranean Sea disappeared.
1. Why trees form kilometer rings
In the forests of Australia, Canada and Russia, trees sometimes groupedThe mysterious forest rings of northern Ontario / CBC so that they create peculiar rounded patterns. Rings of less dense thickets, up to 90 meters wide and up to two kilometers in diameter, are invisible during a walk on the ground, but are clearly visible on aerial photographs. Scientists estimate that there are at least 8,000 of these patterns on the planet.
And until now, science cannot answer why it occurs to all sorts of pines and Christmas trees to grow strictly in a circle. If in the case of patterns in the fields, which are supposedly left by aliens, everything is explained by the enthusiasm of the locals, stakes and wire, then this will not work here.
No one will plant kilometers of forest for the sake of a joke, just to puzzle geographers.
There are several hypotheses regarding this forest phenomenon.
Initially, Canadian scientists decided that giant colonies of fungi settled on the roots of the studied spruces, which often take on a ring shape. Due to the fact that the mycelium pulled juices from the roots, the plants partially died out in a circle. But further researchJ. J. Veillette. The enigmatic rings of the James Bay Lowland: a probable geological origin / Geological Survey of Canada did not confirm the presence of parasitic fungi.
Another more likely explanationS. M. Hamilton. Spontaneous potential and redox responses over a forest ringSP and redox of forest rings / Geophysics: soil bacteria somehow cunningly affect the acidity of the soil and inhibit the growth of trees in the rings.
Also have optionsJ. F. Giroux. Dynamics and morphology of giant circular patterns of low tree density in black spruce stands in northern Quebec / Canadian Journal of Botanythat these are hidden kimberlite pipes with magma that make the trees grow like that, or underground gas pockets prevent the trees from roaming, or the circles are traces of long-standing meteorite falls. But there is still no clear answer.
2. What are skyquakes
The rumble during earthquakes is a frightening, but more or less familiar thing. However, sometimes a terrible noise comes not from the bowels of the planet, but from above.
The phenomenon that received titleEarthquakes, Tides, Unidentified Sounds, and Related Phenomena. Sourcebook Project "skyquake" was felt in Japan, Russia, India, Ireland, England, Norway, the Netherlands, Argentina, Brazil, Jakarta, Italy and in many other places. The Japanese call it uminari, literally "cries of the sea". But a skyquake cannot be related to the ocean, because it happens far from the coast.
A distant but extremely booming thunder sounds from the heavens, although there is no lightning, thunderstorms, or even clouds.
The origin of skyquakes is unknown. They are trying explainS. Claflin-Chalton. Sound and Light Phenomena: A Study of Historical and Modern Occurrences collisions of the coronal matter of the Sun with the upper layers of the Earth's atmosphere, meteors, resonance from solar or terrestrial magnetic activity. As well as volcanic eruptions, the echoes of avalanches, emissions of gas or air from underground and underwater caves, or simply featuresD. K. wilson. Sound Propagation in the Nocturnal Boundary Layer / Journal of the Atmospheric Sciences atmospheric acoustics, when thunder from an ordinary thunderstorm is heard farther than it should be.
But science does not yet have an exact answer why this happens.
3. Where did water come from on Earth?
Earth differs from other planets in the solar system in that approximately 70% of its surface is covered by oceans of liquid water. Many other celestial bodies also have it, but not in such quantities. And still not quite clearHow Did Water Come to Earth? / Smithsonian Magazinewhy there is so much water on our beloved globe.
There is no consensus among scientists. Majority believesA. Peslier. Water in the Earth's Interior: Distribution and Origin / NASA/ADSthat shortly after its formation - about 4.6 billion years ago - our planet had no more water than sand-dry Mercury. But later - 4.1-3.8 billion years ago, during the period of the so-called Heavy Bombardment - many asteroidsR. Gomes. Origin of the cataclysmic Late Heavy Bombardment period of the terrestrial planets / Nature. And some of them brought with them whole mountains of ice. from it and formedMost of Earth's Water Came from Asteroids, Not Comets / Space oceans.
Other researchers thinkG. Buddha. Molybdenum isotopic evidence for the late accretion of outer Solar System material to Earth / NASA/ADSthat Earth received most of the water when a certain protoplanet called Theia crashed into it.
Because of this collision, the Moon also turned out at the same time.
There is also a theory that asteroids with their ice are just a trifle, but the bulk of the water formedEarth’s water may have been inherited from material similar to enstatite chondrite meteorites / Science along with the Earth itself from an accretionary cloud of gas and dust that orbited the young Sun in the early stages of the formation of our system.
There are two proofs for this. Firstly, in the earth's crust such water reserves hiddenWhere did Earths water come from / Astronomythat the oceans are just puddles in comparison. Secondly, in samples of lunar soil delivered by the Apollo 15 and Apollo 17 missions, foundCommon source for Earth and Moon water / Nature traces of hydrogen and deuterium, characteristic of the Earth. So, water came to the moon from our planet.
And, finally, the most original hypothesis, which, however, has many good reasons, says that the liquid came to the planet from the Sun. Yes, on our star eatWater on the Sun / Science water, but, of course, not liquid, but vaporous - after all it's hot there.
Most of all such steam is in the area of spots. From there, together with the solar wind, the oceans blew to the Earth. At least so claimStudy suggests Sun is likely an unaccounted source of the Earth's water / Phys.org employees of the University of Glasgow.
But in order to unambiguously determine the origin of our oceans, there is still not enough data for astrophysicists.
4. Why is it raining meat
March 3, 1876 in Bath County in the state of Kentucky in the USA between 11 and 12 o'clock in the morning from the sky fellThe Great Kentucky Meat Shower mystery unwound by projectile vulture vomit / Scientific American several pieces of meat. This was noticed by the wife of a local farmer, Mrs. Ellen Crouch, who consideredT. Tryniski. Old Fulton New York Post Cards happened by the hand of God.
A few gentlemen from the University of Transylvania collectedKentucky Meat Shower: Alien animals, vulture vomit? Mystery remains / Courier Journal samples of these sediments and kept in a jar for science. Two especially brave ones even tasted the meat.
According to eyewitnesses, it tasted like lamb or venison. But one local hunter named Ellington swore that the meat belonged to a bear.
Newark Science Association study showedWhen It Rains Animals: The Science of True Weather Weirdness / Gizmodothat these are cartilage and muscles, as well as the lung tissue of either a foal, or - horror! - a human baby. Babies have similar lungsKentucky Meat Shower / Everything by structure to horses, so you know.
Similar cases at the same time were fixedC. fort. The Book of the Damned elsewhere in Europe. For example, a little later, on March 12, 1876, there was also precipitation in London, fragments of which resembled veal.
In general, much is known phenomenaWhen It Rains Animals: The Science of True Weather Weirdness / Gizmodowhen all sorts of things fall from the sky that you don’t expect from there. Frogs, fish, tennis balls and other interesting things. In Honduras, in the city of Yoro, for example, it rains regularly from fish, so in May the locals even have a festival in their honor. suitLluvia de Peces (Rain of Fish) – Yoro, Honduras / Atlas Obscura.
Most of these cases are explained by the fact that tornadoes capture objects, lift them into the sky and air masses carry them to other places. But it is hardly possible to imagine that a tornado, before sucking a whole ram or horse, would first butcher them.
There are a couple of theories explaining this kind of rain in Kentucky. For example, meat couldC. fort. The Book of the Damned be colonies of nostocs - cyanobacteria that live in the seas. Periodically, they, captured by sea typhoons, fall from the sky. They look like unappetizing cartilage.
Another optionThe Great Kentucky Meat Shower mystery unwound by projectile vulture vomit / Scientific American: Poor Mrs. Crouch just got sick of a flying vulture. These birds get flying sickness from stress. But the exact reasons for what happened have not been established.
5. Were Earth's Oceans Purple in the Past?
Now our planet is blue, green and white when viewed from space. But scientists suggest that there was a period in history when the Earth could boast of other shades.
Chlorophyll is the main pigment that allows all plant organisms to photosynthesize, from tiny algae to hundred-year-old sequoias. And it is green.
But microbial geneticists at the University of Maryland have good reason believeEarly Earth Was Purple, Study Suggests / Live Sciencethat the first plant cells that lived on Earth some 2.3 billion years ago usedS. Das Sarma. Early evolution of purple retinal pigments on Earth and implications for exoplanet biosignatures / International Journal of Astrobiology a simpler and more effective retinal is a purple or pink chromophore.
Retinal, by the way, is contained in the eyes of all vertebrates, including humans. With its help, the retina converts light into metabolic energy, which allows us to see.
The purple analogue of chlorophyll is also used by archaea halobacteria - one of the most ancient inhabitants of our planet. They remember (well, figuratively speaking) those times when there was no oxygen on Earth yet.
It is more than likely that the early plant cells that learned photosynthesizeS. Das Sarma. Early evolution of purple retinal pigments on Earth and implications for exoplanet biosignatures / International Journal of Astrobiology, were similar to them, and not to the current algae. But then something went wrong, and green cyanobacteria, the ancestors of today's algae, oustedWas Life on the Early Earth Purple? / Astrobiology purple and became the dominant species. And archaea remained on the margins of history.
It is still difficult to say how much the “Purple Earth theory” is true, since from a paleontological point of view, finding the remains of bacteria two billion years ago is very problematic. But if retinal was indeed the dominant chromophore, the waters of the Earth at that time would have looked like the pink Lake Hillier on Middle Island off the coast of Australia.
6. Why the Mediterranean Sea dried up, but came back
Video: Wikimedia Commons
In the Miocene, 5.96 million years ago, the Mediterranean Sea dried up, turning intob. Cunliffe. On the Ocean: The Mediterranean and the Atlantic from prehistory to AD 1500 into two tiny puddles with a maximum depth of 3 to 5 kilometers. And geologists are still wondering why this happened.
This event is called the Messinian salinity crisis.
To this day in the Mediterranean remainedb. Cunliffe. On the Ocean: The Mediterranean and the Atlantic from prehistory to AD 1500 bottom areas where the salt lies in several layers - the research vessel Glomar Challenger counted 11 during drilling. This "pie" is at least two kilometers thick. And these are the consequences of the Messinian crisis.
It's hard to imagine that going onJ. Gargani. Mediterranean Sea level variations during the Messinian salinity crisis / Geophysical Research Letters at the bottom of a dry sea, but the conditions there were so-so. Very salty soil where nothing but the harshest extremophile bacteria could survive, three or four very salty lakes, extreme dryness and temperatures as high as 80°C. In a word, the current Death Valley in America, compared to the Mediterranean Sea, was just a resort.
The causes of the crisis are still unknown. Perhaps some unaccounted for tectonic factors had an effect, or the climate in the middle of the Cenozoic began to behave strangely. But how exactly it happened that Gibraltar took and disappeared, and the entire Mediterranean Sea disappeared after him is unclear. By the way, there is evidence that for the company and the Red Sea could dry upJ. Gargani. Evaporite accumulation during the Messinian Salinity Crisis: The Suez Rift case / Geophysical Research Letters.
Approximately 5.33 million years ago, the sea gradually filled up again through the Strait of Gibraltar and took on its modern shape. But geologists claimZ. x. Li, D. A. D. Evans, J. b. Murphy. Supercontinent Cycles Through Earth Historythat it might disappear again.
Firstly, due to the increased salinity compared to the Atlantic, water evaporates faster here. And secondly, Africa is running out - crawling for itself and crawling to the north, you see. And when this happens - in about a thousand years - a new mountain range will grow in place of the expanses of water.
So it's worth visiting the Mediterranean while it's still on the map.
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