How Likely Is It That an Asteroid Will Collide with Earth in the Next Millennium?

Astronomers managed to make the largest prediction of asteroid impacts on Earth, which tells us how much danger there is of collision in the next 1,000 years.

Isabel Cara

Asteroids have been considered by such brilliant minds as Stephen Hawking as a threat to Earth. In that sense, space agencies have taken it upon themselves to map the sky for objects that could pose a danger of collision. Fortunately, so far, this has not happened, but astronomers continue to search for dangerous trajectories, and now claim to have calculated the trajectories over the next thousand years.

Is the Earth in Danger?

According to astronomers at the University of Colorado, Boulder, there is no reason to fear. They’ve calculated how many large asteroids have a chance of hitting Earth in the next 1,000 years. The answer? Probably none of them, so we can rest easy.

But you may wonder, then why so many headlines about potentially Earth-hazardous objects are popping up. To understand this, you must imagine that the Earth is not alone at all, there is a lot of cosmic debris close to it, and it has even managed to trap mini-moons in its gravitational field, which currently accompanies our natural satellite.

Asteroid collision earth probability 1 - how likely is it that an asteroid will collide with earth in the next millennium?
Green circles represent near-earth objects, yellow squares represent comets, and gray dots represent all other asteroids. Credit: nasa/jpl-caltech/psi

It is to be expected that outer space is full of objects such as asteroids that could end up impacting the Earth, so much so that more than 60 million years ago, the dinosaurs ended up becoming extinct due to the impact of an asteroid 10 kilometers in size. But here comes the good news again, researchers have searched for the largest asteroids and then calculated their trajectories, and it is very unlikely that any of them will cross our path.

NASA has previously estimated that such an event, where an asteroid larger than 1 kilometer in size, only occurs once every few million years. However, the only problem was that it could not be completely ruled out, until now.

The Most Extensive Prediction So Far

Oscar Fuentes Muñoz of the University of Colorado and his research team believe they have cleared up the latent threat from nearby asteroids. The NASA-compiled catalog of asteroids larger than 1 kilometer and close to Earth is believed to be 95% complete, so the team used it to predict the trajectories of the largest objects over 1,000 years.

“Assessing impact risk at longer timescales is challenging, as the uncertainty around orbits grows. To overcome this limitation, we analyzed the evolution of the Minimum Orbital Intersection Distance (MOID), which constrains the closest possible encounters between the asteroid and the Earth,” explains the team.

Asteroid collision earth probability 2 - how likely is it that an asteroid will collide with earth in the next millennium?

They used a different method than those previously used, in which they modeled when asteroids were expected to approach Earth in their orbit and pushed such estimates up to a millennium into the future.

“We came up with a computationally less intensive approach to take a look at a longer time interval,” says Davide Farnocchia of NASA’s Center for Near-Earth Object Studies at the Jet Propulsion Laboratory in California, a co-author of the study. By identifying “the fraction of the orbit that can bring the object closer to Earth,” the team was able to model impact risks much farther out than has been possible with other methods.

During the calculations, only one asteroid caused astronomers’ concern. The so-called 1-kilometer-wide 1994 PC1 has a 0.00151% chance of passing within the lunar orbit in the next 1,000 years. While the probability is extremely small, it is 10 times greater than the risk posed to the planet by any other asteroid.

There is still a chance that a Chicxulub-like event could happen again, that is, at some point, something will collide directly with the Earth, the good news is that it will not happen before the year 3000.

Story written in Spanish by Alejandra Martínez in Ecoosfera

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