A photo from open sources Image from NASA.gov Largest – 4034 Vishnu is only 800 meters wide. This is the length Burj Khalifa in Dubai, albeit with a much larger mass, reports RT. For comparison, the Tunguska meteorite, which devastated hundreds kilometers of the Siberian taiga when it fell in 1908, it is estimated was no more than 100 meters. An asteroid that maybe led to the extinction of dinosaurs 65 million years ago probably had up to 10 kilometers across. But 4034 Vishnu who was discovered in 1986, will pass almost 23 million kilometers from the surface of the earth. The closest of the four, EN 89, will fly by a distance of just over 5 million kilometers from the planet. Asteroid It was discovered only two weeks ago. 
Photo from open sources Image from NASA.gov Although in household understanding, asteroids, ancient cosmic bodies that are not transformed into planets, and fly far away, they are still classified by astronomers as “closely passing” bodies. In total difficulties several hundred of them fly by every year, but this it is unusual that several will appear at once in one day. The closest major asteroid that approached Earth this year was 50-meter DA14, which flew at a distance of 27,600 km from surfaces in February of this year Noteworthy that day, an asteroid up to 20 meters in size penetrated the atmosphere of our planet and exploded over Chelyabinsk, in Siberia. On average, asteroids of this size enter the atmosphere every 10 years. Those like the Yucatan meteor, who may have completed the Mesozoic era is expected able to affect earthly life every 20 million years. At that while the ways of many asteroids can be calculated for centuries forward (and space wanderers can even be destroyed if they are capable of striking the Earth) many, such as Chelyabinsk meteorite, are not detected until they fall into the atmosphere. The planet is potentially vulnerable to impact, which is millions of times more powerful than the worst of nuclear explosions. But, some people are more positive about asteroids. Earlier this year Astrorank, a company that estimates the composition of asteroids taking into account future operations on space mining, said that 4034 Vishnu, consisting mainly of made of platinum and nickel-iron, it costs about $ 40 trillion dollars. This represents more than half of the gross national product in world last year.
NASA Chelyabinsk
