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.

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.

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 ...

Keeping Earth safe from asteroids isn’t just spotting them – it’s also helping people understand what a high-impact probability with Earth means.

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.

We propose a modified jackknife variance estimator which is defined for any without-replacement unequal probability sampling design in the presence of imputation and non-negligible sampling fraction.

Upper bounds are established for the probability that, in sampling without replacement from a finite population, the sample sum exceeds its expected value by a specified amount. These are obtained as ...