Image from NASA.gov
The largest — 4034 Vishnu is only 800 meters wide. This is — the length of the Burj Khalifa in Dubai, albeit with a much larger mass, according to RT. For comparison, the Tunguska meteorite, which devastated hundreds of kilometers of Siberian taiga, where he fell in 1908, it is estimated that was no more than 100 meters.
The asteroid, which may have led to the extinction of the dinosaurs 65 million years ago, probably had up to 10 kilometers in diameter.
But Vishnu 4034, which was discovered in 1986, will be nearly 23 million kilometers from the Earth's surface. The closest of the four, EN 89, will fly at a distance of just over 5 million kilometers from the planet. The asteroid was discovered just two weeks ago.
Image from NASA.gov
Although the common comprehension, asteroids, ancient cosmic body that are not transformed into the planet and fly away, they are still classified by astronomers as a "close pass" of the body. In total, several hundred of them fly each year, but it's unlikely that there will be several in one day.
The nearest large asteroid will approach the Earth this year, was a 50-meter DA14, which flew a distance of 27,600 km from the surface in February Notably on the same day, an asteroid the size of up to 20 meters penetrated the atmosphere of our planet and exploded over Chelyabinsk, Siberia.
The average size of the asteroids enter the atmosphere every 10 years. Those, like "meteor Yucatan," which may have ended the Mesozoic Era, as expected, can affect life on earth once every 20 million years.
While the path of many asteroids can be calculated for centuries in advance (and cosmic wanderers may even be destroyed if they are able to hit the Earth), many, such as Chelyabinsk meteorite, do not show up until they are released into the atmosphere. The planet is potentially vulnerable to the effects, which is millions of times more powerful than the worst of the nuclear explosions.
But, some people have a more positive attitude to asteroids. Earlier this year Astrorank, a company that evaluates the composition of asteroids with respect to future operations, production space, said Vishnu 4034, consisting mainly of platinum and nickel-iron is worth about $ 40 trillion dollars. This represents more than half of the gross national product in the world last year.