Latest news with #YR24
Yahoo
25-06-2025
- Science
- Yahoo
How do scientists calculate the probability that an asteroid could hit Earth?
I was preparing for my early morning class back in January 2025 when I received a notice regarding an asteroid called 2024 YR4. It said the probability it could hit Earth was unusually high. As defending Earth from unexpected intruders such as asteroids is part of my expertise, I immediately started receiving questions from my students and colleagues about what was happening. When scientists spot an asteroid whose trajectory might take it close to Earth, they monitor it frequently and calculate the probability that it might collide with our planet. As they receive more observational data, they get a better picture of what could happen. Just having more data points early doesn't make scientists' predictions better. They need to keep following the asteroid as it moves through space to better understand its trajectory. Reflecting on the incident a few months later, I wondered whether there might have been a better way for scientists to communicate about the risk with the public. We got accurate information, but as the questions I heard indicated, it wasn't always enough to understand what it actually means. The 2024 YR24 asteroid has a diameter of about 196 feet (60 meters) – equivalent to approximately a 15-story building in length. At the time of the announcement in January, the asteroid's impact probability was reported to exceed 1%. The impact probability describes how likely a hazardous asteroid is to hit Earth. For example, if the impact probability is 1%, it means that in 1 of 100 cases, it hits Earth. One in 100 is kind of rare, but still too close for comfort if you're talking about the odds of a collision that could devastate Earth. Over time, though, further observations and analyses revealed an almost-zero chance of this asteroid colliding with Earth. After the initial notice in January, the impact probability continuously increased up to 3.1% on Feb. 18, but dropped to 1.5% on Feb. 19. Then, the impact probability continuously went down, until it hit 0.004% on Feb. 24. As of June 15, it now has an impact probability of less than 0.0000081%. But while the probability of hitting Earth went down, the probability of the asteroid hitting the Moon started increasing. It went up to 1.7% on Feb. 24. As of April 2, it is 3.8%. If it hits the Moon, some ejected materials from this collision could reach the Earth. However, these materials would burn away when they enter the Earth's thick atmosphere. To see whether an approaching object could hit Earth, researchers find out what an asteroid's orbit looks like using a technique called astrometry. This technique can accurately determine an object's orbit, down to only a few kilometers of uncertainty. But astrometry needs accurate observational data taken for a long time. Any uncertainty in the calculation of the object's orbit causes variations in the predicted solution. Instead of one precise orbit, the calculation usually gives scientists a cloud of its possible orbits. The ellipse enclosing these locations is called an error ellipse. The impact probability describes how many orbital predictions in this ellipse hit the Earth. Without enough observational data, the orbital uncertainty is high, so the ellipse tends to be large. In a large ellipse, there's a higher chance that the ellipse 'accidentally' includes Earth – even if the center is off the planet. So, even if an asteroid ultimately won't hit Earth, its error ellipse might still include the planet before scientists collect enough data to narrow down the uncertainty. As the level of uncertainty goes down, the ellipse shrinks. So, when Earth is inside a small error ellipse, the impact probability may become higher than when it's inside a large error ellipse. Once the error ellipse shrinks enough that it no longer includes Earth, the impact probability goes down significantly. That's what happened to 2024 YR4. The impact probability is a single, practical value offering meaningful insight into an impact threat. However, just using the impact probability without any context may not provide meaningful guidelines to the public, as we saw with 2024 YR4. Holding on and waiting for more data to refine a collision prediction, or introducing new metrics for assessing impacts on Earth, are alternative courses of action to provide people with better guidelines for future threats before adding confusion and fear. This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Toshi Hirabayashi, Georgia Institute of Technology Read more: An asteroid impact could wipe out an entire city – a space security expert explains NASA's plans to prevent a potential catastrophe NASA's robotic prospectors are helping scientists understand what asteroids are made of – setting the stage for miners to follow someday NASA successfully shifted an asteroid's orbit – DART spacecraft crashed into and moved Dimorphos I have been studying planetary defense, particularly being part of past, ongoing, and future small body missions. I was part of the NASA/DART mission. I am currently part of the NASA/Lucy mission and the ESA/Hera mission. I am also on the Hayabusa2# team, led by the Japanese Aerospace Exploration Agency (JAXA), as part of an international collaboration. I have no affiliation with JAXA.
CBC
21-02-2025
- Science
- CBC
Why do the chances of an asteroid striking Earth keep shifting?
Scientists have said an asteroid known as 2024 YR24 could collide with Earth in 2032. The odds of such a strike keep shifting, but the most likely scenario remains that the asteroid will miss.
Yahoo
20-02-2025
- Science
- Yahoo
Why asteroid 2024 YR4 has reached a record level on ‘impact hazard' scale
The inventor of the Torino Impact Hazard Scale has explained how scientists are working to 'pin down' the position of asteroid YR24. Professor Richard Binzel tells Yahoo News that it is 'perfectly natural' that the odds of impact will 'bounce around' at this point. The asteroid 2024 YR4 is ranked at three on the Torino Impact Hazard Scale, higher than any previous asteroid bar Apophis which briefly achieved four in 2004. The risk of a huge asteroid hitting Earth has dropped after Nasa reported its highest-ever impact probability for an object of its size. Space rock 2024 YR4, estimated to be 130 to 300 feet wide (40 to 100 metres), now has a 1.5% chance of colliding with Earth in December 2032, the agency said. On Tuesday, Nasa had put the impact probability at 3.1%, the highest ever recorded for an object of its size. The Torino Impact Hazard Scale was adopted in 1999 to offer a way to communicate asteroid impact danger to the public. Used to describe potential impacts within the next 100 years, it ranges from zero ('No Hazard', classified as white) to 10, red (A collision is certain, capable of causing global climatic catastrophe that may threaten the future of civilization as we know it'. Asteroid 2024 YR4 is ranked three (green): Nasa describes level 3 asteroids as a "close encounter, meriting attention by astronomers. Current calculations give a 1% or greater chance of collision capable of localised destruction." The time of closest approach to Earth (when it could potentially impact) is 22 December 2032. The inventor of the Torino Impact Hazard Sale, Richard Binzel, Professor of Planetary Science at Massachusetts Institute of Technology, tells Yahoo News it was proposed in 1997, and adopted at a conference in Torino (Turin) Italy in 1999, by the International Astronomical Union (IAU). It was proposed at the same time as a rise in the number of surveys of near-Earth objects (NEO) meant that knowledge of potential impacts would rise, Binzel says. Astronomers are targeting telescopes at 2024 YR4 to get better readings of its position. The asteroid is currently heading away from Earth and astronomers will use increasingly large telescopes until May, when it will pass out of view. Binzel says 'It is perfectly natural that the impact chances for asteroid 2024 YR4 will bounce around a bit. 'The way it works is that the uncertainty for where the asteroid will be in the future stretches out into a long thin shape like a fettuccine or spaghetti noodle that spans all the way across the orbit of the Moon around the Earth. Earth just happens to lay underneath that noodle, and the fraction that the Earth occupies is the probability of impact. More tracking data will allow astronomers to 'shrink the noodle', Binzel explains. He says, 'As the noodle shrinks, but still happens to include the Earth, it can make the calculated probability go up. 'The good news is that eventually we will pin down the asteroid's position to that of a single grain. Most likely that grain will not be on top of the Earth. It could be even farther than the Moon.' It is too soon to know where it might land if it did hit Earth. However, the UK is not within the current predicted 'impact risk corridor', which is the area where the asteroid could land, according to the International Asteroid Warning Network (IAWN). This corridor stretches across the eastern Pacific Ocean, northern South America, the Atlantic Ocean, Africa, the Arabian Sea, and South Asia, the IAWN said. If the asteroid hits it could cause 'severe blast damage' as far as 50 km (31 miles) from the impact site, scientists say. There is a 0.8% chance the asteroid will impact the moon, Nasa said. It is difficult to accurately predict any potential damage. NASA says that a 100-metre asteroid has 10 times the destructive force of the 2021 Tonga volcanic eruption, which caused a large explosion and tsunamis in several countries. The damage caused by such an explosion would vary depending on where the asteroid hit. "An asteroid this size impacts Earth on average every few thousand years and could cause severe damage to a local region," the ESA has said. NASA says that the impact could kill up to a million people, "averaged over all possible impact locations". "These deaths could result from a direct hit or by tsunami (tidal wave) in the event of an ocean strike," it adds. An asteroid thought to have been around 18m across 'blew up' over the Russian town of Chelyabinsk in 2013. During the 2013 Chelyabinsk event, 1,500 people were injured and 7,300 buildings were damaged by the intense overpressure generated by the shockwave at the Earth's surface.
