The 2015 TB145 object was first discovered in 2015 and brushed Earth just a few days later, on October 31, coinciding with the celebration of Halloween. The chance was that it also had the shape of the dark sign Harry Potter saw for the first time in the fourth book (or film) of the saga. The mark of Voldemort is a skull from which a snake appears, but in this case 2015 TB145 is just a skull that traverses the air.vista.

Although it will pass close to the earth, it will be difficult to see it with the naked eye and it will not be as close as 1,112 days ago -more than 3 years-that's the time it takes to meet us again, that is, the job period. In this case it will go further, one million kilometers away from us. However, at that moment it passed 486 thousand kilometers from the earth or, what is the same, 1.3 times the distance between the moon and the earth.

Actually, "we know little" about this asteroid, says Javier Licandro, research coordinator in the Institute of Astrophysics of the Canary Islands (IAC). For example, we know its size: 650 meters in diameterthat is, it has 109 meters more than the skyscraper One World Trace Center, raised in ground zero of New York. Similar sizes have Ryugu and Bennu asteroids, which are currently studying space agencies Japanese and American, who will bring monsters to earth for study with the Hayabusa 2 and Osiris-Rex.

And we also know something important, that it is not asteroid but a comet. A subtle difference because it is sometimes difficult to differentiate, but important.

Extinct comet

Although it was initially classified as an asteroid, everything indicates that it is not and that we stand for a "sleeping or extinct comet" because of the "type of job" that it has. But what does this mean? "Comets are basically ice balls, dust and stones," explains Licandro. Hipertextual. When they pass close to the sun, the researcher adds, sublimates the ice, that is, "goes from solid to gas".

"In this new state it escapes and carries dust and that produces the tail or comma that is seen in comets." Comets look very clear because they generate a sort of enormous temporary atmosphere because of the water vapor that is thrown out of the surface. It comes out when it gets hot, but at the same time the dust comes out or comes back to the surface and that's it forms a layer of dust that can cover the entire comet until it is deactivatedthat is to say, it does not allow the ice that remains below that layer to warm up sufficiently to sublimate and produce the gas outlet ", illustrates the researcher from the IAC.

The researcher also confirms that "it is very similar to comets", but it is not the only one: "It is very black, and comets are extremely dark, reflecting less than 5-6% of the light it receives". "The comet is like a very dirty snowball and covered with very dark dust. It has a high content of organic materials"However, the exact composition is unknown because" there is not much spectrum data or something like that ".

About the peculiar shape of the comet's skull that will pass on November 11, Licandro states that "it really looks like someone looking at the clouds and says he sees a sheep, it is our imagination more than anything else".

Is it a danger to the earth?

Astronomers catalog the asteroids and comets that pass in the vicinity of the earth, among other things on the basis of the possibilities they have for influencing our planet. 2015 TB145 is cataloged as "potentially dangerous" as Licandro notes. However, there is nothing to fear. This classification only means that "in the future or in centuries can clash, that is, the possibility that this happens is not zero, but it does not mean that it will happen. Most likely it will never crashbut it can happen in hundreds or thousands of years ", adds Licandro.

Do not worry, because scientists are also very controlled on this type of objects: "These objects they are mainly followed by the possibility of a collision with the earth and because such a large object can cause an a very significant disasterLicandro explains: "An object like this could put an end to civilization as we know it," illustrates the IAC researcher, but it would be even worse if it were bigger: "One kilometer in diameter would cause massive extinctions. that would include our species "This is not the case, so for the moment we do not have to worry about this hypothetical situation.

Cometa 2015 TB145. Credit: NAIC-Arecibo / NSF

In summary, what we know from 2015 TB145 is small: we do not know the exact composition, but we do know its diameter and it looks like an extinct comet. In 2015 it went very close to the earth, so it is cataloged as "potentially dangerous" and astrophysicists have it very controlled, though will not come so close to the earth in the coming decades – Their closest approach will not be earlier than in 2088 and even then it will be at a distance comparable to three years ago.

However, the approach of this November 11th will help researchers to study a bit more and to have more information about the call, informally, as a comet Halloween.

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