In the past it has happened that some meteorites are so big and so heavy that they violently hit the Earth forming huge craters several kilometers in diameter! In fact the Earth is hit by about 1000 tons of meteorites every day but most are so small, a fraction of a millimeter, that they go unnoticed or look like dust.
Sometimes some meteorites have done immense damage, shaving entire forests and burning all the trees by exploding in the air or touching the ground.
Recent falls include the 1794, when 200 meteorites fell from the sky over the city of Siena in Italy. In 1803, the village of Aigle in France (Orne) was bombed by 3000 meteorites!
In 1908, a meteorite fell in eastern Siberia at Tungunska and ravaged 200,000 ha of forest, fortunately virtually uninhabited. We felt its echo 600 km away and even in America the seismographs recorded the impact.
In 1969, in Allende, Mexico, large meteorites fell on a village and fragments were collected within a radius of 25 km!
Finally, every 2-3 years a meteorite weighing ten kilos falls on a house or a car as was the case in Peekskill near New York in the United States in 1992 and Japan and Australia in 1995 …
Meteorites and asteroids are very dangerous because if the biggest fall on a city, they can kill millions of people by exploding. If they fall into the sea they can create a tidal wave and flood all cities on nearby coasts and also make hundreds of thousands of deaths in minutes. It is for this reason that astronomers constantly monitor the sky and calculate the trajectories of all the asteroids that come a little too close to the Earth. We will come back to the frequency and the risk of impact.
If one of them collides with our planet in a month or a year, astronomers and the military will try to deflect it from its path. The risk of collision is very low but not zero and each year small asteroids approach the Earth at the distance of the Moon, sometimes even closer. In 1972, an asteroid was so close to the Earth that it entered the atmosphere but fortunately it returned to space. This object still weighed 1000 tons!