Asteroid's Odds of Hitting Earth Went Up. But Not Why You Think
Arthur T Knackerbracket has processed the following story:
It's certain that recently discovered asteroid 2024 YR4 will swing close to Earth in 2032. The chances of an impact remain low - but with relatively limited observations so far, the odds are in flux.
On Jan. 31, the collision impact probability was 1.4 percent. As of Feb. 7, NASA reports it's 2.3 percent, which also means a 97.7 percent chance of missing our humble blue world. But don't be surprised if that number climbs higher: It's normal for the impact odds to increase before falling or disappearing completely.
[...] Asteroid 2024 YR4 - spotted by a telescope from the NASA-funded Asteroid Terrestrial-impact Last Alert System - has been deemed an object worthy of close monitoring because of its size. "Currently, no other known large asteroids have an impact probability above 1 percent," the space agency explained. It's between 130 to 300 feet wide, enough to be dubbed a "city-killer" asteroid - if it indeed hit a city. (For reference, the asteroid that hit Arizona 50,000 years ago and created the 600-foot-deep "Meteor Crater" was 100 to 170 feet, or 30 to 50 meters, across. "A similar-size impact event today could destroy a city the size of Kansas City," David Kring, an impact cratering expert at the Lunar and Planetary Institute, explained in a NASA blog.)
Telescopes will refine the asteroid's orbit around the solar system over the coming months, until it travels too far away to observe (it will return again in 2028). And this added information may likely, though temporarily, boost its Earth impact odds. That's because the asteroid's risk corridor or area of uncertainty around Earth will shrink as astronomers can better define its orbit. But as long as Earth remains in that estimated hazard area - like a catcher's mitt awaiting a high-speed baseball - its relative odds of getting hit increases as the possible range of uncertainty shrinks.
"Earth is taking up a bigger percentage of that uncertain area," Betts explained. "So the impact percentage goes up."
Yet space is vast. And at the same time the area of uncertainty is shrinking, more observations reveal and shift where exactly this zone of uncertainty is. The shrinking area typically moves off of Earth, meaning our planet is no longer in that potential impact area. This happened with the asteroid Apophis - a 1,100-foot-wide behemoth that once had a small chance of impacts in both 2029 and 2036. But more precise telescope observations moved Apophis' range of trajectory off of Earth. The impact probability then plummeted.
"It dropped to zero," Betts said.
"It's a funny thing about homing in on an asteroid and calculating its path, future position, and probability of impacting Earth - it will often appear risky during initial observations, get riskier, and then suddenly become entirely safe," the European Space Agency noted.
Related:
Huge 'God of Chaos' Asteroid to Pass Near Earth in 2029
Asteroid Shock: NASA Preparing for 'Colossal God of Chaos' Rock to Arrive in Next 10 Years
Feared Apophis Impact Ruled Out - Asteroid Will Pass Close Enough to Earth to See with Naked Eye
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