How real asteroid threat?

Asteroid with part number RB1 2016 opened by astronomers on 5 September this year. Saw scientists from the Observatory Catalina Sky Survey (Tucson, AZ). This celestial body is quite unusual, its diameter is only 7 to 16 meters. On 7 September he went at 40000 miles from Earth. In other words, astronomers learned of the existence of 2016 RB1 just two days before the close approach of an asteroid with the Earth, and the asteroid closer to our planet at the minimum distance.

Program, NASA Near Earth Object Program deals with the study and classification of celestial bodies that pose a danger to Earth and of our entire civilization. But, as you can see, this program fails to detect all near Earth celestial body, representing a potential danger for us. There remains a lot of unknown objects? Anyway — how asteroids are actually a threat, maybe to follow them is not worth it?

2016 RB1 due to its size is not dangerous. Even if he fell to the Ground, significant damage would not have happened. Now the asteroid has gone to Venus. With it, he will come closer to the minimum distance in October 2017. Then, in 2020, the asteroid will again be close to Earth. But further than last time. Scientists say that there is no particular danger — a collision is excluded.

7 Sep with the Ground approached another asteroid, much larger than the 2016 RB1. The diameter of the object (catalogue number 2004 DQ41) is much larger and is more than a kilometer. The minimum distance at which the asteroid closer to our planet amounted to 15 million kilometers. To worry too much about.

But we know that the Earth is repeatedly faced with large celestial bodies in his past. One of these collisions occurred only three years ago.

Then, on 15 February 2013 in the Earth's atmosphere hit a relatively small asteroid, dubbed "the meteorite "Chelyabinsk". A drop of this heavenly body was accompanied by a series of atmospheric explosions. In the Chelyabinsk region found quite a lot of fragments of the object with a total mass of 654 kg. According to experts, the age of the object is more than 4 billion years.

This asteroid, according to scientists, originally a single unit with a larger celestial body. But about 300 million years ago it split off from the main body as a result of some event. During this event occurred heating the object up to 650 degrees. Tens of thousands of years ago already splinter the asteroid collided with another celestial body, becoming even smaller.

His weight at the time of entry into the Earth's atmosphere was approximately 13 000 tons, diameter was 20 meters. In the Earth's atmosphere celestial body disintegrated, some fragments reached the surface of the planet. All this has triggered a number of destruction in the Chelyabinsk region. There were also affected, although there were no victims (although victims 1613 — that's huge). But if the asteroid was little more the consequences of the fall of such heavenly bodies on the Earth could be much more severe.

In the past our planet's quite a lot of cases drop a fairly large asteroid that has repeatedly caused disasters. Traces of certain collisions are not left due to the fact that the geological activity of the planet, erosion, volcanic activity and have it all erased with time. However, a number of "scars" are so powerful that they turned out to be possible only to mitigate, but not to destroy completely. Many scientists even suggest that the Moon was formed when Earth's collision with a major celestial body. "Crash" happened about 4.53 billion years ago. In addition, in the time period from 4.1 3.8 billion years ago on Earth often fell asteroids and comets. On the moon from this period were very well marked.

On Earth such traces too, and not one. For example, the Arizona crater, which is 30 kilometers West of the city of Winslow. Crater size is very large. Its diameter is 1219 meters, the depth is 229 metres. The edges of the crater rising above the plain of 46 meters. This is one of the most well-studied craters. He appeared relatively recently — only about 50 thousand years ago. Scientists believe that the crater was formed in the fall a 50-meter meteorite, which weighed 300 tons and was flying at a speed of 45-60 thousand km/h. the power of the explosion from the fall is equal in power 8000-type atomic bombs "Fat man". If such a meteorite would have fallen now, the consequences of the fall would have strong negative consequences for people.

But it's nothing compared to what misery and destruction could cause an asteroid equal in size to that heavenly body, which caused the appearance on Earth of the Chicxulub crater. It is an ancient impact crater with a diameter of about 180 km and a depth of 17-20 km (referring to the original depth). It is located on the Yucatan Peninsula.

Scientists believe that the crater was formed 65 million years ago in the late Cretaceous period. Diameter then fallen to Earth asteroid estimated at 10 kilometers. The energy of the fall was 100 teratons TNT. The consequences were catastrophic. It's a tsunami height of 50-100 meters, fires all over the Earth, active volcanoes. Followed by climate change, like nuclear winter. Some experts suggest that this asteroid was one of the reasons for the extinction of dinosaurs. Others don't agree with them. Anyway, if a giant asteroid fell to the Earth, now, our civilization in its current form would cease to exist.

Asteroids that pass dangerously close to Earth, are not such a rarity. More recently, astronomers learned to detect the asteroids before they pass by earth, or falling on its surface. In 2008, the asteroid was discovered for the first time. He received the catalogue number 2008 TC3. It is a small piece of rock with a diameter of about 4 meters and weighs 80 tons. The day after the discovery object entered the Earth's atmosphere and exploded somewhere in the Nubian desert.

Five years later, in 2014, was again discovered an asteroid headed for Earth. Object 2014 AA size 2-4 meters entered the Earth's atmosphere later, 21 hours after its discovery. He fell into the ocean.

Surveillance and more surveillance
Generally speaking, asteroids are frequent guests in the system Moon-Earth. One of the last large object, asteroid 2004 BL86, was discovered in January of last year. This 300-meter rock passed within 1.2 million kilometers from Earth, three times further from us than is the Moon. According to physicist Mark boslough (Mark Boslough), an asteroid 20 meters in diameter pass through the geostationary orbit every two years. Similar asteroids pass through the orbit of the moon about once a week. 40-meter objects pass near the Earth (at a distance approximately equal to the distance from the Earth to the moon) several times a year.

Alan Harris, an astronomer, an expert on asteroids, said that about 200 million objects with a diameter of 6 meters and more are our neighbors. That is, such objects may not be constantly close to the Ground. But their orbits are close by, and sooner or later we see them nearby. Harris claims that about once in two years fall to the Ground objects with a diameter of 6 meters and above.

To monitor dangerous neighborhoods NASA uses a system Catalina Sky Survey. All the detected objects that may pose a danger to the Earth, cataloged. In 1998, the US Congress mandated NASA to detect at least 90% of the "neighbors" of the Earth with a diameter of 1 kilometer or more. In 2005, Congress instructed NASA to track asteroids, the size of which is 140 meters and above.

Watching out for asteroids not only NASA, so now scientists have a fairly detailed map of the orbits of potentially dangerous for the Earth, celestial bodies with a detailed classification of these bodies. At the moment there are over 12,000 objects, of which 1% is comet, and all the rest of the asteroids. Some of them are very large, their diameter is a kilometer or more. The size of most — from 100 to 300 meters. Such asteroids could cause major destruction on Earth, similar to the effects of nuclear bombing.

How dangerous are asteroids?
Very dangerous. The threat from our nearest neighbors-the asteroids is very real. According to experts, the asteroid of equal destructive power of the Tunguska meteorite falls to Earth about once in 500 years. Asteroids equal in size to what was the cause of the formation of meteor crater, appear on our planet every few thousand years. But the giants, like the asteroid that created the crater Chikalovski, falling every hundred million years. But all this statistics. A giant can fall to the Ground in the next year and through 100 million years.

As mentioned above, such giants is the end of our entire civilization. Smaller asteroids can cause severe local destruction within a single country. But we can only guess about the consequences of such damage, even if an asteroid of small size will fall somewhere in a densely populated industrial region.

12 000 close to the Earth asteroid — that's not all. According to some specialists, their number is higher and can reach 200 thousand (a diameter of 100 meters and above). But the problem is that asteroids with a diameter of less than 100 meters pose to people a significant risk. 25-meter object can cause significant damage in the scale of the city and suburbs. Everything larger is already a regional problem. Even more global.

How to protect yourself?
The main task of humanity now is the mapping of potentially dangerous celestial bodies. this is to cope NASA and other organizations. But the picture is still incomplete. And even the task of detecting 90% of potentially dangerous objects is not all that needs to be done. After all, some of the asteroids, which were not included in the number of observables, may already approach the Ground with great speed. Now scientists have discovered and catalogued around 50% of the close to Earth objects with a size from a few hundred meters and above.

Work must continue. And this is even more important that in our system, may appear new, previously unknown to scholars objects. It is possible guests from the asteroid belt or even the Kuiper belt. And in the Oort cloud, according to the calculations of astronomers, can be more than 2 trillion comets. Maybe some of them unknown to the scientists, is already out on the trajectory that will lead it to Earth? It can be.

The main threat is just not a belt of asteroids which have been studied fairly well, and referred to a distant region of space that we don't know almost nothing. The threat is the small asteroids that are not tracked. Refers objects the size of a meteorite "Chelyabinsk". Global issue they are not, but if such an asteroid will fall somewhere in a densely populated region, is a pleasant effects of this can not be called. And to detect them if possible, at the last moment, just before the fall.

Asteroid threat to most people seems insignificant and unrealistic. In fact, everything is much more real than most people believe. Of course, this does not mean that now we need to begin to worry more about asteroids, earning a nervous breakdown. But to know and understand the problem you need.

Now NASA launched OSIRIS-Rex (Origins Spectral Interpretation Resource Identification Security Regolith Explorer), is a probe that needs to study asteroid Bennu. Besides the study of celestial bodies, the probe needs to take rock samples and take these samples back to Earth. Expected time of return — 2023. NASA think the asteroid is one of the most dangerous known to man celestial objects. In 2135 year, it will be only 300 thousand kilometers from Earth.

Creating an effective system of detection of asteroids, development of security is what you need to mankind. This is not an isolated country, and the world community.



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