What is the risk of asteroid impact?

The least asteroid effects occur about twice a year. Only about 3 m (10 ft) on average, these rocks, which are 17 km/s average, have enough energy to cause double the size of the hirosima bomb at an altitude of 43 km. Originally, there were concerns that the impact on atmospheric asteroids would be wrong as nuclear explosions of the sky satellites and launched a nuclear war, but modern satellites are able to distinguish the characteristic double flash nuclear bombs. The Royal Astronomical Society considers anything less than 50 meters to be a "meteoroid". Meteoroids are commonly known as "falling stars". As with smaller asteroids, asteroids around this size usually lack kinetic energy to get to the surface and explode in airbath burster at an altitude of about 7 km. Airburst energy is about 6 TNT megatons, which corresponds to a small hydrogen bomb. It is assumed that the asteroid around this size exploded above the area near the river Tunguska inIn 1908, creating a circle of burned trees 50 kilometers (30 miles) on average. This is called the Tunguska event and has helped to encourage government around the world to risk the impact of the asteroid more seriously.

The effects of the bolides asteroids around 250 m (820 ft) occur on average only once every 2,000 years. In fact, these asteroids tend to hit the surface, even if they may break slightly before. The resulting energy is around the gigaton, about 20 times larger than the strongest nuclear weapon that has ever been tested, Tsar Bomba. It is assumed that such an impact of asteroids occurred on the Moon in 1178, where it was recorded by a monk in Canterbury, England. This class of impact leaves a crater miles across.

Asteroids greater than 1 km (0.62 Mi) on average are relatively rare and occur less than once every 50,000 years. However, they are the most devastating and most likely threatening human race, despite their rarity.Such an asteroid impact releases 50 energy gigatons in energy value in its source and ignite everything more than a few hundred miles in all directions. If such an asteroid hit a populated area, millions of people could kill. The probability that one will hit in the next 100 years is less than 1/500 and the probability of accidental intervening of the inhabited area is less than 1/1 000.