asteroid to Earth - a cataclysm of global proportions.It always led to changes in the climate of our planet, because of which died out a huge number of species of living organisms.According to one of the most credible hypothesis, that the fall of an asteroid caused the Permian-Triassic extinction event about two hundred and fifty million years ago.Permian extinction, although it is not too well known to the general public, was much more tragic than the famous dinosaur extinction seventy million years ago.In the first case died before 96% of the species of marine organisms (such as plants and animals).On land the situation was not much better: lost seventy percent of terrestrial vertebrate species and eighty-three percent of species of insects.Such mass extinction of insects in nature was no more, because these arthropods is extremely easy to adapt to a changing environment.
second disaster was much less devastating, but then, too, there was a replacement of biological dominance, which led to the emergence and development of mammals.Hypothesis number one - the same asteroid.In the first case, the scientists point to Wilkes Land crater in Antarctica, which, in their opinion, was formed by the fall of this asteroid, the second - in the Chicxulub crater in Mexico.
Wilkes Land crater has a diameter of five hundred kilometers.It is completely hidden under the Antarctic ice shell, so it is impossible to study.But in 2009, his radar was conducted research and found that it has a shape characteristic of impact craters formed on the site of a large asteroid or meteorite.Chicxulub Crater is much smaller and has a diameter of one hundred and eighty kilometers.That is the size of the fallen asteroid depends scale extinction of terrestrial organisms.
Astronomers no consensus about what kind of impact event - the fall of the asteroid, and some - the fall of the meteorite, comet or something else.Researchers at the sky can not decide what should be classified as celestial bodies to asteroids, and what - to meteorites and even planets.Seven years ago, pundits have decided to allocate a new class of celestial bodies.It recorded several large asteroids and demoted from the rank of this planet Pluto.The class decided to be called "dwarf planets."Innovation is not universally accepted, as many astronomers challenged the feasibility of the new classification.
happen in mid-February, the event stirred up Russia, and especially - the Urals.The meteorite, which fell in the vicinity of Chelyabinsk, specialists from NASA considered the largest of the observed humanity after the Tunguska.In memory of the people it was a meteorite that caused the most damage and injuries.Although he fell apart before reaching the ground, he managed to make a lot of troubles, even destroying the shop of one of the Chelyabinsk Plant.The press reported that the meteorite - a harbinger of an asteroid that will pass close to Earth, and it is probable that it will fall in the gravity field of our planet.
Interestingly, the meteorites in the Urals become something almost habitual, own, native.The relatively small area Chelyabinsk region (less than ninety thousand square kilometers) over the past seventy-five years for the third time became the center of attraction of visitors from outer space.In 1941 and 1949, in the northern area of the city Katav-Ivanovo and the village Kunashak also falling meteorites, though much smaller.All three can be connected to the crash site almost straight line length of no more than two hundred and fifty kilometers.Such meteorites concentration on a limited area in a short period of time is not found anywhere in the world.Well, just some kind of mysticism!
accident in the Urals revealed that we are vulnerable to bombardment from space.In Russia, began the development of a ten-year program for protection from cosmic threats.
