A few days ago we heard about the asteroid 2023 DW for the first time. In the early days the news talked about about a one chance in 600 that it impacted the Earth and that astronomers had assigned the rock a one on the Torino scale (or Turin) as a way of classifying your risk. Scientists have since lowered this index to zero. The question is, what does this mean?

First of all, a bit of context. 2023 DW it is one of the so-called near-Earth asteroids (NEAs), space rocks whose orbital path is close to ours, making an impact, however unlikely, possible. the asteroid It was discovered in February of this year and the first calculations about its orbit assigned it a chance in 850 of crashing into us.

This probability of impact varied over the days since its discovery, first upwards and now downwards. The latest estimate published by CNEOS (Center for the Study of Near-Earth Objects) at the time of writing this article estimated an impact probability in 3,600, or which is the same, a 0.028% chance of crash. This last calculation has brought with it the change in the Torino scale, 2023 DW went from one to zero.

the stopover of torino It is an index that goes from 1 to 10 and measures the risk posed by an asteroid. As a measure of risk, it combines two factors: the potential damage that the event could cause and the probability of impact. This combination, instead of being represented as an estimated damage, is presented as a number between one and 10.

The potential damage that an asteroid can cause is measured based on its size and the kinetic energy it would carry the impact. The larger the asteroid (and assuming a constant velocity) the higher the energy and further destruction.

The events with the lowest risk are those with an index of 0 or 1. If 0 implies a negligible collision probability, 1 does not represent much else. According to CNEOS, this category is assigned to “routine discoveries whose near-Earth passage does not imply an unusual level of danger.” In other words, a “normal” risk.

Values ​​from 2 to 4 on the scale are reserved for events that require the attention of astronomers. These categories range from a “more or less close, but not highly unusual near Earth” pass; up to “a 1% or greater probability of a collision capable of causing regional (scale) devastation”. In this case, also it is considered that public attention may be justified if the collision is expected in a period of less than 10 years.

The “orange” or threat zone ranges from 5 to 7. Descriptions of these levels range from a “serious but uncertain” risk of damage on a regional scale to a “very close” encounter with a large object capable of causing a planetary scale catastrophe.

The “red zone”, from 8 to 10 is reserved for certain collisions, that is, when the probability of impact is close to 100%. The difference between these three categories responds to different levels of impact power, from those that can cause localized destruction to those that can pose a threat to our civilization.

## Odds that come and go

The scale is intended to be adjusted as astronomers’ calculations are refined. After all, the search and tracking of potentially dangerous objects depends on observations made millions of kilometers away and complex mathematical models.

This has led not only to the change in the value assigned to 2023 DW on the Torino scale, but also to several weeks of adjustments in the impact probability assigned to this asteroid. An asteroid that, it should be remembered, never posed a big risk among other reasons due to its small size (about 50 meters in diameter).

Anyone who has been following the news related to this asteroid may have noticed a slight dance of odds in terms of its impact. The history of observations of the asteroid shows how the adjustments in its probability were first made upwards, leading to an estimate of an impact probability out of 360.

From there the adjustments were downward. The reason for this change in trend is curiously counterintuitive. The predicted trajectory of the asteroid passed close to Earth. Associated with that expected trajectory, astronomers calculate an area of ​​uncertainty. As the observations adjust, the area of ​​uncertainty becomes smaller.

Since the size of the Earth does not change, the relative portion of this area that our planet takes is increasing. Until the area of ​​uncertainty no longer encompasses our planet. It is then that the probability of impact begins to drop sharply.

This is the surveillance systems success story. But there are still many asteroids that are beyond our control. As we improve our ability to detect hazards, we also advance in our ability to deal with them.

The most advanced plan in this regard is the one tested by the DART asteroid redirection mission. 6 months ago NASA crashed a space probe into the asteroid Dimorphos and recently we have known that the impact managed to slightly deviate the trajectory of the rock. The plan is that if an asteroid could pose a risk to Earth, a new probe would be sent to divert it just enough to avoid hitting our planet.

In Xataka | We have spent billions on the DART mission to make it crash. For now he is on the right track

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