Sci-One. The most dangerous threats from space

    In the history of the Earth there were at least five mass extinctions of flora and fauna. The largest disaster happened about 250 million years ago. Then for some reason, 95% of all creatures on the planet died. Among the versions of the causes of extinction there are several associated with real threats from space. And this is not some fantasy about aliens or evil gods. So what can come from the depths of interstellar space and cause a global catastrophe? And how do we predict such a threat? The main problem of humanity here is that people do not take cosmic threats seriously. And in vain. A space strike is a matter of time. Watch the video of our friends from Sci-One, and read the text version under the cut.



    Supernovae


    According to statistics, in the visible part of the Universe, every second there is at least one explosion of a star. If a star is several times larger than our Sun, then with the exhaustion of hydrogen in its core, it usually turns into a supernova . And the larger the star, the faster the “tank” is exhausted - in just a few million years. Gravitational collapse occurs . The radius of the "defeat" of supernovae is several tens of light years.



    Hard radiation resulting from a flash ionizes nitrogen and oxygen in the atmosphere of the Earth, which forms nitrogen dioxide . In large quantities, it can have a catastrophic effect on the protective ozone layer of our planet. But this is not all: the interaction of nitrogen dioxide with water vapor forms nitric acid, which precipitates in the form of harmful rains. Together, the hard ultraviolet radiation and abundant acid rain can destroy vegetation on Earth (in the film " Interstellar " such a total catastrophe is shown, when humanity is left without a chance to grow something). And in addition to everything, nitrogen dioxide will reduce the transparency of the atmosphere, which can cause global cooling.

    Gamma bursts


    The gamma-ray burst , the most powerful energy release in the Universe, can also destroy the Earth . In just a few seconds, energy is released as much as our Sun radiates over 10 billion years. Scientists have not yet come to a common opinion that is the source of gamma-ray bursts, the most severe form of electromagnetic radiation. It could be collapsing massive stars.



    With a gamma-ray burst, some researchers have linked the Ordovician-Silurian mass extinction on Earth, which happened about 450 million years ago. Then, living creatures lived mainly in the seas and oceans. And, according to recent estimates, 85% of species of marine fauna died. From such a catastrophe we will most likely not be saved unless mankind migrates in advance from the planet. But the good news is that in the coming millennia, it seems, we are not threatened to be in the zone of the gamma-ray burst. In our galaxy, this happens very rarely, and there are no stars nearby that could make such an unpleasant surprise.

    Comets and asteroids


    Not all threats can be noticed in time. In our solar system, according to the most approximate estimates, there are about three thousand "invisible" comets. They almost do not reflect light, because they have partially evaporated - they have lost water and gases. In 1983, one such comet was noticed, only this happened almost by accident and after it flew near the Earth. Unnoticed, it passed 5 million kilometers from our planet - closer than any other comet in the past 200 years. Of the estimated 3,000 "invisible" comets, mankind today managed to track only 25.

    The asteroid threat is also quite real. Most asteroids are concentrated within the asteroid belt.between the orbits of Mars and Jupiter. But sometimes they collide with each other or under the influence of gravity of larger objects leave their usual orbits.

    The UN has even created an international warning network: if astronomers notice a potentially dangerous asteroid, then the United Nations Office for Outer Space Affairs should organize a rescue mission.



    Scientists and engineers are considering many scenarios for saving the planet. The most famous and obvious is the destruction of a potentially dangerous object. Like, for example, in the movie Armageddon . But what can happen to an asteroid if you try to destroy it? Scientists from Los Alamos Laboratorymodeled the explosion of a 1 megaton atomic bomb on the surface of an asteroid measuring 500 by 150 meters. As shown by calculations, this should be enough to avoid the threat of a big blow. But one cannot guarantee that the asteroid wreckage will not hit the Earth with a grape shot. So that they are completely burned in the atmosphere and do not reach the surface of the planet, each of them must be less than 30 meters in diameter.



    Other simulations of protection against asteroids using nuclear explosions: one , two .

    True, mankind has no more or less effective way to save the Earth from a really big boulder. According to NASA, as of January 2016, more than 700 thousand asteroids were discovered in the solar system. The agency even created a separate page on its website.where you can see when and what objects are flying towards the Earth and how dangerous they are. But there is no unified tracking system yet. Although celestial bodies as small as 100 meters are capable of arranging a regional catastrophe on Earth, those that are more than a kilometer away will leave little chance for humanity. Such attacks will generate giant explosions, a shock wave from a collision will bypass the globe. Part of the kinetic energy will be transmitted to the earth's crust and will cause earthquakes and tsunamis. To assess the potential danger of convergence, two scales are used - Turin and Palermo . They are similar, but the second is somewhat more complicated. Both scales take into account the kinetic energy of the object and the likelihood of a collision with the Earth.

    One of the largest proven impact craters located in South Africa - its diameter reaches three hundred kilometers. In 2005 it was added to the UNESCO World Heritage List. According to modern estimates, the Vredefort crater appeared after an asteroid hit with a diameter of 5 to 10 kilometers - enough to destroy all of civilization. The fall of the Lessefort asteroid caused numerous earthquakes and tsunamis, and the thermal shock wave generated by it could have caused fires around the world. As a result, the emission of large amounts of soot and carbon dioxide into the atmosphere led to climate change, depriving the planet of sunlight for several years. Perhaps it was this disaster that put an end to the domination of the dinosaurs, but for now this is not a generally accepted theory.

    The sun


    One of the most familiar threats at first glance is flashes on our Sun. More precisely, coronal mass ejections . They look very beautiful. You can often hear that these emissions cause geomagnetic storms that can affect people's physical well-being and mood. The Federal Reserve Bank of Atlanta even conducted a studyon this topic. It proves that the coronal emissions of the Sun so affect the exchange players that they become disheartened and become inclined to immediately get rid of the shares. Can you imagine any kind of flashfire and crazed traders start selling stocks in large quantities? This can provoke a panic, because of which the world economy will collapse in a couple of days. And then - war, hunger, disease. Although a number of scientists still doubt that coronal emissions can influence humanity in this way. So far, no direct link has been confirmed between our physical state, behavior, and geomagnetic storms, which are triggered by particularly aggressive impacts from solar plasma streams.



    Nevertheless, the Sun will still be able to finish off modern civilization with its own wind alone, if it tries. And the further, the higher the danger. Coronal emissions can occur several times a day. On average, for one emission, our star gets rid of 10 billion tons of plasma. It looks like this: a closed loop of twisted magnetic field lines breaks off from the Sun. It carries with it a clot of plasma from electrons and protons with a small amount of helium, oxygen and other elements. This loop is drawn into the interplanetary space, and a “bundle” can form that wraps around a plasma clot - then a magnetic cloud is obtained. “Striking” the Earth’s magnetosphere, it causes very strong disturbances in near-Earth space.

    The strongest recorded geomagnetic stormsoccurred in 1859and is known as the "Carrington Event." During the storm, large-scale failures and disconnections of telegraph communication were observed in Europe and North America, and in magnetic observatories the arrows of the magnetometers rested against the edge of the scale. The Northern Lights could be seen all over the Earth, even in the Caribbean. Emissions like this occur on the Sun about once every 500 years. The modern world is so strongly dependent on electricity and electronics that today a similar storm would cause great damage to civilization. Due to the oscillations of the magnetic field, induction currents will appear in the multi-kilometer transmission lines. Overloads will begin, whole systems will be shut down due to them. The lights will go out, the elevators will stop and the electric transport will start, interruptions in water supply will begin, medical equipment will cease to work in hospitals, industrial accidents will occur. In short almost every sphere of people's lives will suffer. Electricity can turn off on entire continents, and recovery would take months and years.

    And the last, largely unexpected consequence of flares on the sun - the swelling of the atmosphere. In 1979, this had already led to an uncontrolled descent from orbit and the fall of the first and only American orbital station Skylab to Earth. Anomalous radiation can not only disable many satellites in near-Earth space, but also affect the operation of onboard equipment of passenger aircraft - more than 8,000 of them fly daily in the sky. By the way, something similar could happen in 2012, but the Earth and the main stream Plasma missed.

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