Parallax · space desk · — 21

The odds moved. The asteroid did not.

An asteroid's chance of hitting Earth once read 1 in 32. Six days later, 1 in 25,000. The rock you were watching never moved.

Same rock, same orbit, the whole time. In February 2025 the odds of it hitting Earth read about 1 in 32. Six days later, 1 in 25,000. Nothing moved out there. What changed was how well anyone knew where it would be.

The odds of hitting Earth fell from 3.1% to 0.004% between 18 and 24 February 2025.

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.

Same rock, different number

Spotted in December 2024. Peak Earth odds in February 2025. Ruled out six days later, and then the risk shifts to the Moon and climbs through 2025. Cleared on 5 March 2026. Read the dates and one thing holds under all of them. The orbit never changed.

Dec 27 2024
Found by ATLAS, in Chile.
Feb 18 2025
Earth-impact odds peak at 3.1%.
Peak odds. The orbit was at its least known.
Feb 24 2025
Earth ruled out. Odds 0.004%.
Jun 3 2025
Lunar odds climb to 4.3%.
The risk moves to the Moon. The rock does not.
Feb 18 & 26 2026
Webb makes two faint detections.
Mar 5 2026
Lunar impact ruled out. Zero.

The fifteen-month arc

Six figures from the whole episode. Peak Earth odds 3.1%, about 1 in 32. Peak lunar odds 4.3%. Size 53 to 67 metres. Miss distance more than 20,000 km. Only the size belongs to the rock. Same asteroid, same orbit, the whole time.

Asteroid 2024 YR4 · key figures, Dec 2024 to Mar 2026
3.1 %
Peak Earth-impact odds
Set on 18 February 2025, when the orbit was known least well.
0.004 %
Earth odds after resolution
Six days later. Earth is out, for 2032 and beyond.
4.3 %
Peak lunar-impact odds
3 June 2025, the high point. Europe's space agency later called it around 4%.
53–67 m
Estimated diameter
The miss distance is three to four lakh times this width.

What actually changed

The agency that published every one of those numbers explained the last update in one sentence. The change reflected improved precision about where the asteroid would be in 2032, rather than a shift in its orbital path.

“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

NASA's own words

That's the short version. The full issue rebuilds the whole odds machine.

Full issue · 6 sections · 8 sources, all linked

Read the full issue →