Our beloved blue planet is constantly being hit by space debris, but due to the fact that most space objects burn up or fall apart in the atmosphere, this most often does not present any serious problems. Even if an object reaches the surface of the planet, it is most often small, and the damage it causes is insignificant.

However, of course, there are very rare cases when something very large flies through the atmosphere, and in this case very significant damage is caused. Fortunately, such falls are extremely rare, but it’s worth knowing about them, if only to remember that there are forces in the Universe that can disrupt people’s everyday lives in a couple of minutes. Where and when did these monsters fall to Earth? Let's look at the geological records and find out:

10. Barringer Crater, Arizona, USA

Arizona apparently couldn't get enough of the Grand Canyon, so about 50,000 years ago it added another tourist attraction when a 50-meter meteorite landed in the northern desert, leaving behind a crater 1,200 meters in diameter and deep. at 180 meters. Scientists believe that the meteorite, as a result of which the crater was formed, flew at a speed of approximately 55 thousand kilometers per hour, and caused an explosion more powerful atomic bomb, dropped on Hiroshima, approximately 150 times. Some scientists initially doubted that the crater was formed by a meteorite, since there is no meteorite itself, but according to modern scientists, the stone simply melted during the explosion, spreading molten nickel and iron throughout the surrounding area.
Although its diameter is not that large, its lack of erosion makes it an impressive sight. Moreover, it is one of the few meteorite craters that look true to its origin, making it a top-notch tourist destination - just as the Universe intended.

9. Lake Bosumtwi Crater, Ghana


When someone discovers a natural lake whose outline is almost perfectly round, it is quite suspicious. This is exactly what Lake Bosumtwi is, with a diameter of about 10 kilometers and located 30 kilometers southeast of Kumasi, Ghana. The crater was formed by a collision with a meteorite with a diameter of about 500 meters, which fell to Earth about 1.3 million years ago. Attempts to study the crater in detail are quite difficult, since the lake is difficult to reach, it is surrounded by dense forest, and the local Ashanti people consider it a holy place (they believe that touching the water with iron or using metal boats is prohibited, making access to nickel at the bottom of the lake is problematic). And yet, it is one of the best preserved craters on the planet. this moment, and a good example of the destructive power of megarocks from space.

8. Mistastin Lake, Labrador, Canada


The Mistatin Impact Crater, located in the Labrador province of Canada, is an impressive 17 by 11 kilometer depression in the earth that formed approximately 38 million years ago. The crater was likely originally much larger, but has shrunk over time due to the erosion it has suffered from the many glaciers that have passed through Canada over the past millions of years. This crater is unique in that, unlike most impact craters, it is elliptical in shape rather than circular, indicating that the meteorite fell at an acute angle rather than flat, as is the case with most meteorite impacts. Even more unusual is the fact that in the middle of the lake there is a small island that may be the central rise of the complex structure of the crater.

7. Gosses Bluff, Northern Territory, Australia


This 142-million-year-old crater with a diameter of 22 kilometers, located in the center of Australia, is an impressive sight from both the air and the ground. The crater was formed by the impact of an asteroid with a diameter of 22 kilometers, which crashed into the Earth's surface at a speed of 65,000 kilometers per hour and created a crater almost 5 kilometers deep. The energy of the collision was approximately 10 to the twentieth power of Joules, so life on the continent faced great problems after this collision. The highly deformed crater is one of the most significant impact craters in the world and never lets us forget the power of one large rock.

6. Clearwater Lakes, Quebec, Canada

Finding one impact crater is cool, but finding two impact craters next to each other is doubly cool. This is exactly what happened when an asteroid broke into two pieces upon entering the Earth's atmosphere 290 million years ago, causing the formation of two impact craters on east coast Hudson Bay. Since then, erosion and glaciers have greatly eroded the original craters, but what remains is still an impressive sight. The diameter of one lake is 36 kilometers, and the second is about 26 kilometers. Considering that the craters were formed 290 million years ago and were subject to severe erosion, one can only imagine how large they were originally.

5. Tunguska meteorite, Siberia, Russia


This is a controversial point, since no parts of the hypothetical meteorite remain, and what exactly fell into Siberia 105 years ago is not entirely clear. The only thing that can be said with certainty is that something large and moving at high speed exploded near the Tunguska River in June 1908, leaving behind fallen trees over an area of ​​2000 square kilometers. The explosion was so strong that it was recorded by instruments even in the UK.

Because no pieces of meteorite were found, some believe that the object may not have been a meteorite at all, but a small part of a comet (which, if true, would explain the lack of meteorite debris). Conspiracy fans believe that an alien spaceship actually exploded here. Although this theory is completely unfounded and pure speculation, we must admit that it sounds interesting.

4. Manicouagan Crater, Canada


Manicouagan Reservoir, also known as the "Eye of Quebec", is located in a crater formed 212 million years ago when an asteroid with a diameter of 5 kilometers fell to Earth. The crater with an area of ​​100 kilometers, which remained after the fall, was destroyed by glaciers and other erosive processes, but at the moment it remains an impressive sight. What is unique about this crater is that nature did not fill it with water, forming an almost perfectly round lake - the crater basically remained dry land, surrounded by a ring of water. A great place to build a castle here.

3. Sudbury Crater, Ontario, Canada


Apparently, Canada and impact craters are very fond of each other. Singer Alanis Morrisette's birthplace is a favorite place for meteorite impacts - the largest meteorite crater in Canada is located near Sudbury, Ontario. This crater is already 1.85 billion years old, and its dimensions are 65 kilometers long, 25 wide and 14 deep - it is home to 162 thousand people, and is also home to many mining enterprises, which discovered a century ago that the crater is very rich in nickel. for a fallen asteroid. The crater is so rich in this element that about 10% of the world's nickel production comes from here.

2. Chicxulub Crater, Mexico


The impact of this meteorite may have caused the extinction of the dinosaurs, but it is certainly the most powerful asteroid collision in the entire history of the Earth. The impact occurred approximately 65 million years ago when an asteroid the size of a small city crashed into Earth with an energy of 100 teratons of TNT. For those who like precise data, this is approximately 1 billion kilotons. Compare this energy to the atomic bomb dropped on Hiroshima, with a yield of 20 kilotons, and the impact of this collision becomes clearer.

The impact not only created a crater with a diameter of 168 kilometers, but also caused megatsunamis, earthquakes and volcanic eruptions across the Earth, greatly changing environment and sentenced the dinosaurs (and apparently many other creatures) to death. This vast crater, located on the Yucatan Peninsula near the village of Chicxulub (from which the crater gets its name), can only be seen from space, which is why scientists discovered it relatively recently.

1. Vredefort Dome, South Africa

Although the Chicxulub crater is better known, compared to the 300-kilometer-wide Vredefort Crater in South Africa, it is an ordinary pothole. Vredefort is currently the largest impact crater on Earth. Fortunately, the meteorite/asteroid that fell 2 billion years ago (its diameter was about 10 kilometers) did not cause significant harm to life on Earth, since multicellular organisms did not yet exist at that time. The collision undoubtedly greatly changed the Earth's climate, but no one noticed it.

At the moment, the original crater is heavily eroded, but from space its remains look impressive and are a great visual example of how scary the Universe can be.

Dinosaurs are huge lizards, the height of which reached a 5-story building. Their remains are found deep in the earth, which is why scientists say that dinosaurs lived on Earth millions of years ago. The last dinosaurs went extinct about 65 million years ago. And they appeared 225 million years ago. Judging by the remains of the bones of these lizards, scientists conclude that there were more than 1000 varieties of such animals. Among them were large and medium-sized, bipedal and quadrupedal, as well as those that crawled, walked, ran, jumped or flew in the sky.

Why did these giant animals become extinct? There are several theories about their death.

Why dinosaurs became extinct: scientific research facts

Since the death of dinosaurs occurred a very long time ago, we can only build hypotheses based on known scientific facts:

• The extinction of the dinosaurs proceeded very slowly and took millions of years. This period was called “glacial” by paleontologists.
• Over the course of these millions of years, the climate has changed. In the previous era, there were no ice caps on Earth, and the water temperature at the ocean floor was +20ºC. Climate change has caused a decrease in overall temperature and the appearance of significant icing.
• In addition to climate, the composition of the atmosphere changed. If at the beginning of the Cretaceous period the air contained 45% oxygen, then after 250 million years it was only 25%.
• During this period of time, a planetary catastrophe occurred. It is confirmed by the presence of iridium, an element that is located deep in the earth’s core and is also found in asteroids and comets. Iridium is found in deep layers of soil throughout the planet.
• There are indirect witnesses of the collision of the Earth with an asteroid - huge craters. The largest are in Mexico (80 km in diameter) and at the bottom of the Indian Ocean (40 km).
• Along with dinosaurs, some species of lizards (sea and flying) became extinct.

When and how dinosaurs went extinct: theories of disaster

Habitat change

Our planet is changing very slowly but steadily. The climate is changing, new species of animals appear and old species disappear. They find themselves not adapted to life in new conditions.

Cold snap

The average air temperature dropped from 25ºC to +10ºC. The amount of precipitation has decreased. The climate has become colder and drier. Dinosaurs, like other lizards, were not adapted to life in cool conditions.

It is known that most lizards are cold-blooded. When the air temperature drops, they cool down and become numb. However, this theory cannot explain why those reptiles that were warm-blooded and could hibernate became extinct.

Another theory is more viable - as a result of climate change, there is less grass vegetation - ferns, which were eaten by non-predators. Judging by the size of dinosaurs, they needed substantial thickets of food to feed them. As a result of a decrease in the amount of food, gradual extinction began. Herbivores died because they lost food. And the predatory ones - because there were few herbivores (which they ate).

Planetary catastrophe: collision with an asteroid or explosion of a star

Traces of a collision with a celestial body were discovered on the island of Yucatan - a huge crater covered with stones and soil. When the asteroid collided with the earth, a powerful explosion should have occurred, which would have lifted tons of soil, stone and dust into the air. The dense suspension blocked the sun for a long time and caused a cold snap. As a result, not only dinosaurs, but also a number of other reptiles became extinct. This theory is confirmed by the remains of iridium in the soil of the Cretaceous period.

The explosion of a star relatively close to our planet could be the cause of a significant increase in radiation. However, it is not clear why the colossal emissions of radiation left other animals alive. Why dinosaurs became extinct still remains a mystery that haunts the minds of scientists.

Despite many theories, scientists are making computer simulations and reconstructions of what happened many millions of years ago. This is what the film will talk about.

On the pages of the site there are many discussions about what happened on Earth 1000 years ago, 10 thousand years ago. There is complete confusion about who is doing what. And everyone is right as usual. On the one hand, if we don’t know such a “recent” past, how can we know what was there 65 million years ago? Sometimes it seems that we know more about those ancient times. At least quite extensive archaeological research has been done using precise equipment. Or are the dinosaurs fake too?!

So what do scientists report? At the end of the Cretaceous period, i.e. 65 million years ago a huge meteorite fell on planet Earth. It was a planetary catastrophe. Not the first and not the last time. A meteorite that fell near what is now located on the coast of the Mexican Yucatan Peninsula Chicxulub village, left its mark not only in its appearance, but also in the history of the development of life on Earth.

Before this cataclysm, dinosaurs and related reptiles reigned on land, in the air and in the sea. After the catastrophe they became extinct, and mammals and birds took the path of evolutionary development.

The Chicxulub Crater is not a place of legend. It was found in the 1970s, but they did not immediately study it, since the depression was covered with a thick layer of sedimentary rocks. In the 1990s, the crater was examined again, and scientists determined that the date of its formation exactly corresponds to the boundary of the Cretaceous and Paleogene periods.

Dead and survivors

At the site where the Chicxulub meteorite fell, the sky was covered with clouds of dust. Forest fires raged everywhere, adding smoke and soot to the dust. The situation was getting even worse. For several weeks, the sky over the entire globe darkened, the light of the Sun did not penetrate to the surface of the planet, which did not allow plants on land and in the oceans to normally carry out their main function - photosynthesis.

Plants began to die. But they serve as food for herbivores, and these, in turn, feed on predators. Any serious disturbance in the chemical and physical situation on Earth, such as a sharp decrease in illumination or a drop in temperature, instantly affects the flora of the planet. The reverberations of these disturbances reverberated throughout the entire ecosystem.

Probably, after the fall of the meteorite, the microscopic plants of the ocean were the first to die out. Thus, the marine ecosystem collapsed. However, there is evidence that the meteorite only accelerated their death. The seagrass began to die off long before the impact, likely due to major changes in the patterns of ocean currents. On land, it is believed that the meteorite impact not only obscured the Sun, but also caused large-scale fires and acid rain, which caused serious damage to land plants.

A study of rocks at Hell Creek, Montana, showed that more than 75% of plant species in inland North America became extinct after a meteorite impact. It is believed that the most recently emerged flowering plants, as well as some of the plants typical of the Mesozoic era, such as ginkgos and cycads, were hit the hardest. In a short time period after the impact, ferns stood relatively calmly, and in a longer period, conifers quickly recovered. Oddly enough, land plants in the Southern Hemisphere hardly died out, which means that the impact was actually not as catastrophic as some assume.

Gradually vegetation throughout to the globe began to slowly return to lost positions. Flowering plants were the best able to take advantage of the situation. Eventually they diversified into a great variety of species, from small grasses to huge trees, and conquered almost every landscape on the globe.

EXTINCTION

This herbivorous dinosaur, Triceratops, was widespread during the Cretaceous period. By the end of the period they were still thriving and abundant. But then they disappeared, like all dinosaurs.

Among marine fauna, the extinction at the end of the Cretaceous was much more widespread than on land. Among the extinct sea creatures were ammonites that lived in the oceans for 300 million years.

The end of the dinosaur era

Many animals did not survive the disaster. The most famous example is dinosaurs and flying pterosaurs. Along with them, giant marine reptiles such as mosasaurs and plesiosaurs disappeared. There is still debate about why dinosaurs became extinct, while many other groups survived despite the disaster. Thus, bony fishes (12% died out), frogs (0%), salamanders (0%), lizards (6%) and placental mammals (14%) almost did not suffer from extinction.

Dinosaurs were not the only reptiles in that era. Before the Chicxulub meteorite struck, 45 families of turtles, crocodiles, lizards and snakes lived on Earth. Turtles and crocodiles suffered significantly, however, like plants, those who survived soon adapted to the new conditions.

The initial decline in the number and influence of reptiles contributed to the rapid spread of mammals, although they too suffered mass extinctions. About 20% of the ancient mammal families of the Cretaceous period disappeared.

In total, about 75% of animal species disappeared at the turn of the Cretaceous and Paleogene periods. Many of them were already rare and on the verge of extinction, but scientists have not been able to give a reliable explanation of why some species became extinct while others survived. Some biologists believe that extinction or survival was simply a matter of luck.

http://www.3planet.ru/history/terra/1590.htm

The extinction of dinosaurs is one of the most important mysteries of our planet. Why did lizards, which dominated all ecosystems of the Earth for many millions of years, become extinct, and in a relatively short time? Most often, this is blamed on a huge asteroid that fell in the Gulf of Mexico. But, as it turned out, the lizards died not from the darkened sky and acid rain, but from soot from the burnt oil of the gulf. This is the only way to explain why crocodiles, birds and mammals survived the disaster, say the authors of a recent study published in the journal Scientific Reports.

Death or murder?

In world science, the extinction of dinosaurs is most often explained by “catastrophic” hypotheses. Dinosaurs (as well as ammonites and marine reptiles) could be destroyed by volcanic activity, a meteorite impact, a supernova explosion near the solar system, or a drop in sea levels. Domestic paleontologists generally adhere to the biosphere version: dinosaurs disappeared gradually - due to the spread of flowering plants and climate cooling. The evolution of plants gave rise to numerous insects. Small mammals (such as rats) fed on them, as well as on plants. Corresponding small-sized predators, also mammals, arose. They could not threaten adult dinosaurs, but the eggs of the lizards became their prey - after all, due to their size, it was extremely difficult for adult dinosaurs to protect future offspring. These and other unfavorable conditions gradually weakened the viability of the lizards, although there was no direct competition between them and mammals.

In Western paleontology, it is precisely “catastrophic” explanations that predominate. The first violin in this was played by the Chicxulub crater - the third largest on the planet (with a diameter of about 180 kilometers). The crater is believed to have been caused by a huge asteroid impact 65 million years ago. In 1980, American physicist Luis Alvarez and his geologist son suggested that the timing of the fall of the Chicxulub asteroid and the extinction of the dinosaurs was not accidental. One of the main arguments in favor of the meteorite hypothesis is the thin layer of clay that everywhere corresponds to the boundary of geological periods. Alvarez pointed to an anomalous concentration of the rare metal iridium (most likely of extraterrestrial origin) in this layer. It is unclear what role the asteroid played in the birth of the hypothesis that killed the dinosaurs. personal experience Alvarez (he was one of the creators of the atomic bomb), but his version has become very popular over the past 30 years.

The Achilles' heel of the "catastrophic" explanations is that the extinction event lasted several million years and began long before the asteroid impact. So, in 2016, paleontologists found that 24 million years before Chicxulub, certain species of dinosaurs died out faster than new ones were formed. In some biological groups, this process arose 48-53 million years before the disaster. It's likely that dinosaurs (and other extinct groups like ammonites and sea lizards) were already suffering from long-term processes that are still poorly understood, and the meteorite (or other catastrophe) only accelerated the crisis.

Picture: DETLEV VAN RAVENSWAAY/SCIENCE SOURCE

This objection is now being overcome with the help of additional versions: for example, in 2015-2016 about the “double blow” that killed the pangolins. The researchers worked with the Deccan Traps (basalt rocks in western India) - traces of one of the most powerful volcanic eruptions in the history of the Earth. These seismic processes, which released many dangerous volatile compounds into the atmosphere, began 250 thousand years before the fall of the Chicxulub meteorite and continued for half a million years after it (eventually one and a half million cubic kilometers of lava flowed out). These eruptions coincide in time with the fall of Chicxulub. The toxic emissions and volcanic dust that obscured the Sun created a deadly cumulative effect.

Instruments of crime

But why did the fall of an asteroid lead to catastrophic consequences? What were the specific mechanisms of impact on the biosphere? And where does such selectivity come from - dinosaurs died, but not crocodiles, snakes and turtles, ammonites, and not their closest relatives, the nautiluses?

To answer these questions, in April 2016, a marine expedition: geologists from a drilling platform are trying to drill through the Chicxulub crater at the bottom Gulf of Mexico. Rock samples recovered from the sediment can reveal a lot.

Japanese scientists working with bottom sediments of neighboring territories (Haiti) proposed a new explanation: the animals were killed by soot that rose into the atmosphere (there was a lot of it, since Chicxulub fell into the oil-rich Gulf of Mexico). Carbon evidence from corresponding deposits in Canada, Denmark and New Zealand indicates that the asteroid ignited huge amounts of crude oil.

It is generally believed that the impact of Chicxulub caused the planet's atmosphere to become filled with sulfuric acid aerosols. They reflected sunlight - darkness fell, photosynthesis stopped, temperatures dropped (as in a hypothetical nuclear winter), and acid rain began to fall. However, this scenario does not explain the survival of crocodiles, mammals and birds.

Soot emissions seemed like a more realistic scenario to Japanese scientists. They analyzed organic molecules and their isotopes in sediment layers corresponding to the Cretaceous-Paleogene boundary. Soot is easy to identify - it is indicated by polyaromatic hydrocarbons, primarily coronene and benzopyrene.

Soot remains in the stratosphere for many years (even if rain washes it out of the troposphere). Researchers have calculated the impact of emissions on the Earth's climate. Soot actually blocks sunlight, preventing it from reaching the troposphere and the surface of the planet. The water cycle in nature is disrupted, and the amount of precipitation is sharply reduced. If 500 teragrams of soot were released, the light would dim by 50-60 percent, the air temperature at the Earth's surface would drop by 6-9 degrees (for several years), and precipitation would decrease by 40-70 percent. Emissions of 1500-2000 teragrams would increase cooling to 10-16 degrees, and reduce precipitation by 60-80 percent.

Selectivity in choosing a victim

Two unconditional facts established by geologists are a drop in temperature in the Gulf of Mexico and the massive death of land plants from drought in low latitudes (as shown by excavations in Haiti). It was droughts (a decrease in soil moisture by 40-50 percent, if we accept the average emissions scenario) that launched a destructive cycle: the grasses and broad-leaved plants of the tropics dried out, causing soil moisture to drop even more, and so on. The surviving plants were completely eaten up by herbivorous dinosaurs, which led to desertification, the death of large lizards, and then the predators that fed on them. Freshwater crocodiles survived - their food pyramid was based on plant detritus, even in the first critical important years disaster entering the water. Small mammals, birds, fish, and amphibians that crocodiles fed on also survived.

The final calculations led to the assumption that emissions of 500 teragrams of soot would not have led to the extinction of dinosaurs and ammonites, and the maximum simulated “dose” of soot (2600 teragrams) would have created such a global drought and cooling that all large animals would have died, including crocodile Therefore, the average scenario is closest to the real situation - 1500 teragrams. The accompanying moderate cooling and slowdown of photosynthesis in the World Ocean caused the extinction of ammonites, inoceramas (large bivalves) and planktonic foraminifera, but deep-sea marine organisms were almost unaffected.

Paleontologists emphasize that the Chicxulub disaster was not as terrible as it is described. For example, if the particles released into the air created global darkness for even a few years, photosynthesis would stop, and not only dinosaurs, but also all large land vertebrates, including birds and mammals, would become extinct. Despite the cold and drought, most taxonomic groups of plants and animals at order levels and above survived the crisis. However, scientists note that the Cretaceous-Paleogene extinction event proves that even a short-term catastrophic event can irreversibly change the biosphere - a valuable lesson in an era of global warming.

The asteroid that supposedly killed off the dinosaurs 65 million years ago is a dwarf compared to the asteroid that fell on our planet more than 3 billion years ago.

Early in Earth's history, a killer asteroid ripped a hole in our planet about 500 kilometers wide that is longer than the length of the highway between Washington and New York, a new study finds. The space monster unleashed a cycle of destruction like your worst nightmare: "We knew it was big, but we didn't know how big."

Illustration: Donald Lowe, Stanford University. In the center is him, on the right is Mount Everest.

The impact 3,260,000,000 years ago caused the earth to shake, creating earthquakes and raising tsunamis that reached thousands of kilometers, according to information from a new research team.

The size of this destroyer is about 37 kilometers wide, which is more than 3 times the size of the asteroid that killed the dinosaurs 65 million years ago.

Illustration: Donald Lowe, Stanford University.

"We knew it was big, but we didn't know how big," said Donald Lowe, a geologist at Stanford University and co-author of the asteroid study.

Evidence of a colossal impact comes from looking at the Barberton Greenstone Belt in South Africa, which features rocks and "crustal fractures" that are consistent with the idea of ​​a giant impact, scientists say (the asteroid impacted thousands of Earth kilometers, but where is unknown) .

Barberton (in the Transvaal Shield, southern Africa)/ Google.maps

If this information is confirmed, the asteroid could be one of those that attacked the Earth during the so-called late period of heavy bombardment, which overtook solar system between 3 billion and 4 billion years ago, reports infuture.ru.

This single event could even change the way the Earth formed, the scientists added.