The Torino Scale gives asteroid hazards a number from 0 to 10. Zero means no meaningful risk. Ten is a certain collision capable of global catastrophe. YR4 briefly reached Level 3 while its 2032 orbit was still uncertain.
Level 3 calls for serious attention from astronomers when an object has at least a 1% chance of a localized collision within a few decades. YR4 qualified, and observatories responded by squeezing as much information as possible from every viewing opportunity.
Later measurements moved YR4 back to Level 0, but its brief stay at Level 3 remains historic: it became the first object in years to give the public a close look at the scale doing real work. The number captured what astronomers genuinely knew at each stage—and helped focus telescopes on the questions that mattered most.