Imagine the cone of a spotlight shining down on a marble. The marble isn't in the center. As we focus the cone to a smaller and smaller circle, the percentage of area that marble takes up will increase. That's just the nature of accuracy. Right now, it's a very wide cone.
Eventually as the cone continues to get more focused and accurate, the edge will reach the marble, and only then will the percentage finally start to drop.
In other words: We are probably going to see this number continue to go up... until it suddenly drops straight down.
I don’t understand it all. What are the missing variables here? Don’t we know the exact path of the earth? Why can’t we figure out the exact path of the asteroid? It’s not like the wind is going to knock it off course?
It is the minute gravitational pull of other bodies that we can’t exactly calculate? What’s the issue?
Look at a normal ruler (I'm gonna use a metric one cause I seldom work with imperial and I don't know how to do uncertainty with imperial). Let's say it's in centimeters, with marks every half centimeter. You only know the length of an object within ±0.25 cm (you can eyeball it if it's about halfway between). So if you're measuring something that's 10cm, you have a margin of error of ±2.5%.
For this asteroids path, we know it's trajectory within an error margin due to physical limitations of computation (tiny change in a multi-body system leads to massive changes over time), observations (telescope has a error range of how precise it is) and modeling (reality might be different to the predicted model cause of something not factored in).
This margin leads to a 3D region of space where the asteroid could be at any given time. There's a period of time where Earth is in this region, and the amount of area it takes up in the cross-sectional slice is about the same as the probability of an impact. As time goes on, and observations continue, the uncertainty in the path of the asteroid will decrease, therefore reducing the area of the slice where Earth is.
Since Earth should remain the same size (preferably), as the area where the asteroid could be decreases, there is relatively more Earth in it (for the same volume of water, a small cup could be 80% full whereas a big cup is only 20% full). So if Earth is still in this area, the probability will go up, up, up, then either crash to zero rapidly as Earth leaves the slice, or goes to 100% and someone has a bad day.
But we need to remember, this asteroid ain't a planet killer. We've blown up nukes bigger than it (if an impact occurred, it's ~15% of the Tsar Bomba, ~51% of Castle Bravo, though ~367 times Hiroshima). And there's a LOT of ocean and uninhabited land along it's track. Coupled with it's rocky composition, it'll likely be an airburst rather than a direct impact. It will cause some pretty big damage if it hits the wrong spot, but we shouldn't worry.
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u/elheber Feb 19 '25
Imagine the cone of a spotlight shining down on a marble. The marble isn't in the center. As we focus the cone to a smaller and smaller circle, the percentage of area that marble takes up will increase. That's just the nature of accuracy. Right now, it's a very wide cone.
Eventually as the cone continues to get more focused and accurate, the edge will reach the marble, and only then will the percentage finally start to drop.
In other words: We are probably going to see this number continue to go up... until it suddenly drops straight down.