One rock, two very different numbers
What most people think
The odds kept getting revised down, so the whole thing must have been an overreaction that scientists quietly walked back.
What the data shows
3.1% → 0.004%in six days
Those are the odds of an Earth impact, six days apart in February 2025. The asteroid flew the same orbit through both readings, so only the measurement changed: how well anyone knew where it would be.
The risk then moved to the Moon and rose there, before going to zero as well.
The odds of hitting Earth fell from 3.1% to 0.004% between 18 and 24 February 2025.
In plain terms Two panels: on the left what most people assume, on the right what the numbers show, with the one figure that settles it.Source · NASA Planetary Defense blog
Up on Earth, across to the Moon, zero
That six-day drop was one step in a longer sequence. Read the dates downward and the same orbit sits under every reading.
Six dated updates for 2024 YR4. The arc runs from the December 2024 discovery to the March 2026 all-clear.
In plain terms Each entry is one dated update to the odds. The highlighted nodes are the turning points, and the last is where it stands now.Source · NASA Planetary Defense and Webb blogs, with ESA
What these percentages were actually measuring
The sequence you just read is six readings of one orbit. Three terms explain why the readings moved.
- The error box
- The stretch of space the asteroid could be in on the day. Every fresh sighting shrinks it, and the odds are split across what is left inside.
- Impact probability
- The odds that the rock hits us, written as a percentage. It tracks the size of that box, so sharper measurements move the number while the rock stays put.
- The 1% line
- Crossing one percent starts the international planetary-defence notification process. It is a procedure that switches on, nothing more.
Source · NASA Planetary Defense blog
3.1% is about one chance in thirty-two
A percentage is hard to feel. Here is the peak Earth figure, said the way odds usually are.
Peak Earth-impact odds, 18 February 2025
3.1%
NASA has never recorded a higher impact probability for an object this size or larger.
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About one chance in thirty-two. 3.1 out of every 100.
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The same figure turned around: thirty-one chances in thirty-two that nothing happens. The other side of the same figure.
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Six days later, the reading was about one chance in 25,000. From the 0.004% reading in February 2025.
The peak Earth reading of 3.1% is about one chance in thirty-two.
In plain terms One number, large, and beside it the everyday things it equals, so the size can be felt rather than read.Source · NASA Planetary Defense blog
Only one of six belongs to the rock
Those odds describe how well we knew the orbit, so they moved. The size is the one figure here that belongs to the rock itself. The date and the distance belong to the close approach.
Asteroid 2024 YR4 · key figures, Dec 2024 to Mar 2026
In plain terms The headline numbers from the story, each with its unit and a one-line note.Source · NASA Planetary Defense blogs and 2024 YR4 Facts, with ESA Planetary Defence
NASA's own sentence for what changed
Six numbers, and only the size was about the rock. Here is how the agency put it.
“This update reflects improved precision in our understanding of where the asteroid is expected to be in 2032 rather than a shift in its orbital path.”
— Molly Wasser, NASA Science
'Improved precision' means the range of possible positions kept shrinking, so the Moon ended up outside it. The rock is still up there, in the same aasmaan, on the same path it has always flown. On 22 December 2032 it arrives, and it misses.
Source · NASA Planetary Defense blog · 5 March 2026