On February 14, 2046, a small but big enough asteroid will almost certainly hit Earth.
This is usually how you bet about space rocks, but you might get a different impression if you just read the headlines last week when a new asteroid near Earth was discovered. , “NASA Says Asteroids” It could hit Earth on Valentine’s Day 2046.’
However, that “possibility” carried a lot of weight.If you read deeper, you’ll find that chicken littlelings are a little more muted, less likely to affect, and more likely to be less. But these articles will never explain How this reduced likelihood works, indicating why the odds tend to fall. Worse, this kind of “OMG” turns into a “I don’t care” response whenever a new asteroid is discovered, knowing that there’s a non-zero chance of a collision at some point in the vague future. .
Take a deep breath, look at the science, The Hitchhiker’s Guide to Space: Do not panic.
The asteroid in question here is called 2023 DW and was discovered by the MAP Project using telescopes in the high desert of Chile on February 26, 2023. Calculations based on these initial observations, and some calculations several days later, determined that 2023 DW was approximately 50 meters across. It is much larger than the 2013 Chelyabinsk asteroid and resembles an asteroid that exploded in the air in the Tunguska region of Siberia in 1908. And its orbit may bring it very close to Earth.
very close. Calculations showed a 1 in 770 chance of 2023 DW striking Earth on February 14, 2046. A rating of 0 means no impact, and 10 means some impact from a rock big enough to cause a global disaster. The vast majority of new asteroids have a rating of 0, but even a 1 means that the impact cannot be ruled out completely and that some havoc is possible.
Hence the heading. But how worried should we be?
Having been through this situation many times, my answer is simple. See Douglas Adams quote above. First, it’s better to think of a 1 in 770 chance of hitting as a 99.87% chance of not hitting. And almost inevitably, over time, these impact odds will drop further.
This moment of astronomical de-escalation has a lot to do with how we discovered the asteroid, how we characterized its orbit, and most importantly, how these numbers change over time.
Dedicated telescopes around the world search for asteroids every clear night, sweeping large swaths of the sky. Stars don’t move from image to image, but asteroids do. Automated software looks for blips of light and checks them for possible false positives, such as subatomic particles from space zapping the detector, hypersensitive pixels, and more. If the object moves in a predictable way on the image, the software alerts astronomers that a potential space rock has been found. Most of them turn out to be one of the known asteroids, well over a million in number, but dozens of new asteroids are discovered every night.
Astronomers can then measure the asteroid’s position over time and calculate the basic shape of its orbit using mathematics pioneered by Johannes Kepler and popularized by Isaac Newton in the 17th century.th century. This has allowed astronomers to predict where the asteroid might be in the future, concluding that there is an unfortunate possibility that Earth and her 2023 DW will be in the same place at the same time in her 23 years.
However, these initial measurements have inherent uncertainties due to the short baseline of the initial observations. In the limited time period of just a few days, it is difficult, if not impossible, to reliably determine asteroid motion.
Think about it like this: Imagine you were the outfielder at a baseball game. You’re watching the pitcher throw the ball, and the batter makes a powerful swing. Crack! When they hit the ball, it flies in your direction.
Suppose the batter closes his eyes immediately after hitting the ball. can you catch it?
Probably not. I didn’t have time to feel the trajectory of the ball, so I didn’t know where it was going, let alone intercept it with my relatively small mitt. However, the longer you look, the more likely you are to see exactly where it is and play it.
The same applies to asteroids. Imagine watching a telescope move through the night sky almost due east. That little arc isn’t long enough to see if you’re moving north or south a bit. Remember that space also has depth. Over time, the slight deviations from due east accumulate to extend in front of the asteroid’s position like an obscure cone. A month from now it could be anywhere in a large volume of space. Since the Earth can also be in the same volume, the impact can occur.
But Earth is a small mitt in the vast empty outfield. The likelihood of impact in these situations is low. More observations are needed to break through that uncertainty and focus on the asteroid’s true trajectory.
This is where the stats work in your favor. If an asteroid was initially predicted to come very close to Earth, subsequent observations would change that prediction, making it more likely that the calculated path would stray farther from our beautiful planet. but gets longer as time goes on.
And that’s exactly what happened in 2023 DW. Initial observations passed very close to Earth, but more observations were made just days later, shifting the asteroid’s potential path. The most likely orbit now is that her 4.5 million kilometers (more than 10 times her distance to the Moon) missed us in February 2046. It could also pass her eight million kilometers from us, with the minimum distance currently at 2,00,000 kilometers. — that is, it is actually missed and lost in large numbers. This calculated distance can easily grow as more observations are made.
And this is why I’m personally not worried about newly discovered asteroids projected to hit us in the next few years.
Also note that just days after the discovery of 2023 DW, a larger (about 50 meters) asteroid called 2023 DZ2 was discovered. The asteroid will pass Earth just 175,000 kilometers on March 25, 2023. For a short time, it was a 1 in 430 chance. 2026 could have been impacted, but within days the odds had dropped to 1 in 71,000. 2023 DZ was swiftly removed from the NASA/JPL Sentry Watchlist of Potentially Hazardous Asteroids.
go farther Happy For Miss Approaches: Help astronomers come up with better ways to calculate orbits. Asteroids are much easier (and safer) to observe than distant asteroids. And if you get close enough, you can even ping it with radar, revealing its shape. , rotation, rough composition, and much more accurately pinpoint its trajectory.
Instead of getting to the point, don’t panic. Maybe even celebrate! We are safe and can get more science. I call it a good bet.
This is an opinion and analysis article and the views expressed by the author or authors are not necessarily Scientific American.
