In the solar system there are billions of asteroids of all sizes. Sometimes, these asteroids deviate from their orbits, making it possible for them to impact diverse celestial bodies. Throughout its existence, the Earth has suffered the impact of numerous meteorites. The latter has a size that can vary between some millimetres to various kilometres in diameter. The energy that releases a meteorite varies enormously in relation to its size and composition.
Most of the bodies in the solar system are minute and have a very small mass. In its orbit around the Sun, the Earth’s gravitational field attracts a great number of these objects. When entering the Earth’s atmosphere, the small grains of dust and rock disintegrate in a matter of milliseconds, leaving a luminous trail behind them. This is what we name shooting star.
As you might guess, these micro-meteorites don’t represent any danger to the planet, as they don’t get to touch the ground at any moment. In fact, they are a very beautiful phenomenon to see, and we know precisely the days of the year when the most shooting stars can be seen.
Big asteroids against the Earth
As we have seen, the smallest meteorites don’t represent any danger to the planet, as they don’t even touch the ground. However, the solar system is also formed by much bigger objects, being tens or hundreds of kilometres in diameter.
In the case that one of these objects hit the Earth, as it has already happened many times in the history of our planet, a huge amount of energy would be released. This would provoke disastrous consequences, including the death of many animal and vegetal species.
The following list shows the amount of energy that would release meteorites of different sizes when impacting the Earth:
- A meteorite 25 metres in diameter would release the energy of 1 megaton
- One of 50 metres in diameter would release an energy equivalent to 10 megatons.
- A rock of 140 metres would release an amount of energy of 300 megatons.
- A meteorite 300 metres in diameter would release the energy of 2,000 megatons when impacting the Earth.
- One having 600 metres in diameter would produce energy of 20,000 megatons.
- The impact of a meteorite of one kilometre would release the energy of 100,000 megatons.
- One of 5 kilometres in diameter would provoke an explosion of 10 million megatons.
- A meteorite 10 kilometres in diameter would release 100 million megatons of energy when impacting the Earth.
The impact of an asteroid 1 kilometre in diameter could provoke the extinction of humanity in its entirety. In fact, we know that the extinction of dinosaurs and many other animals and vegetal species was caused by the impact of a meteorite of about 10 kilometres in diameter.
Even if it could seem a distant event, it isn’t necessary to go that far away in time to find other big meteorite impacts. For example, in 1908, an object 50 metres in diameter fell onto the Russian region of Tunguska. This meteorite didn’t manage to touch the ground, but it volatilised at a height of 8 kilometres. However, it released energy between 10 and 15 megatons, 1,000 times more than the bomb of Hiroshima.
Luckily, it fell in an uninhabited zone of Siberia, destroying more than 2,000 square kilometres of forests. Moreover, it provoked a shock wave of 5 on the Richter scale, which gave three times the turn of the Earth. The enormous quantity of energy released by the meteorite also generated winds, fires, and the extinction of part of the ozone in the atmosphere.
All these disasters were provoked by a rock 50 metres in diameter, a size a little bigger than a house, that didn’t even touch the ground. If this object had impacted a city, the disasters would have obviously been much more important, and would have caused the death of a great number of persons.