Celebrating the asteroid in his day

Asteroids represent threats to our planet and, also, many opportunities for studying the universe.

In order to educate citizens around the world on the importance of these rocks that roam the space, the United Nations proclaimed the celebration of Asteroid Day every 30th of June.

A disaster 110 years ago

On June 30, 1908, a small asteroid of about 60 meters (comparable to a medium-sized building) fell on Tunguska (Siberia). The impact caused an explosion 1000 times more energy than the bomb of Hiroshima and destroyed some 80 million trees on an area of ​​2,000 square kilometers, which is larger than the area. Gran Canaria Island. If the explosion had occurred on an inhabited area, it would have caused a huge tragedy, says Rafael Bachiller, director of the Astronomical Observatory of Spain (National Geographic Institute) and University of the Royal Academy of Physicians of Spain in its publication in The World of Spain .

More recently, on February 15, 2013, the explosion of a fireball on Chelyabinsk (Russia) amounted to 500,000 tons of TNT (500 kilotonnes of energy) and caused more than 900 injuries and damage to many buildings at least 6 cities. After the explosion in the air, the remains of the meteor fell to the surface of the Earth in the form of many meteorites, the largest of which, a mass of about 650 kilograms , was recovered at Chebarkul Lake. It is thought that Chelyabinsk was the most violent car of the fallen on Earth since the Tunguska event.

About 100 tons of dust particles and rocky materials fall daily on Earth, but fortunately the atmosphere of our planet acts as an effective protective shield because in the friction with the air, these particles and meteorites are completely calcined in their vast majority.

According to the Chelyabinsk experiment, we know experimentally that asteroids start to be dangerous when they exceed a size of 10 or 20 meters. An asteroid of more than 35 meters might be able to destroy a city, a larger one of 140 meters could cause the devastation of an entire region, or a large tsunami in case of a fall on an ocean. A distance greater than one kilometer could cause a global catastrophe.

The Florence asteroid could be seen in September 2017 near the Earth, due to its gigantic size – 4.4 kilometers in diameter on average –

Cataloging Asteroids

It is estimated that there are about 20 million dangerous objects, more than 10 meters, in our environment. Among them, those measuring more than 140 meters are about 14,000; It is estimated that one of them falls on Earth every 50 centuries.

Finally, there are a thousand that measure more than one kilometer. Naturally, the fall of one of these major asteroids is potentially very destructive on Earth either by its bursting in the air, or by the fall of meteorites reaching the surface of the planet. To protect yourself from such a risk, the first step is to locate all potentially dangerous objects and calculate their orbits.

Currently, 95% of asteroids close to more than one kilometer are cataloged; Of these, 158 are classified as potentially dangerous because they have an orbit that brings them closer to 7.5 million kilometers of Earth (about 20 times the Earth-Moon distance). But the knowledge of those of medium size, who are also potentially very dangerous, is much worse.

In 2005, the US Congress asked NASA to locate by 2020 90% of asteroids that could cause serious harm to our planet. However, it is estimated that today we only know, at best, 20% of these objects and that the NASA goal has long been considered realistic.

Of course, once the danger is known, it is necessary to develop the technology needed to divert the trajectory of a large asteroid observed on the way to Earth. The firing of projectiles capable of fragmenting the object or modifying its orbit is probably the best-known proposition, although there are other possibilities, such as landing a plane. ship on the asteroid capable of applying the necessary impulse to deflect it in a safe direction.