Near-Earth object watch · Asteroid 2024 YR4
Daily notes, observations, and context as we track asteroid 2024 YR4.
The quick version
About YR4
YR4 is a space rock roughly as wide as a 15-to-20-story building—and on December 22, 2032, it will sweep through the Earth–Moon neighborhood. Early observations gave astronomers a real reason to calculate a possible Earth impact, while later measurements revealed an extraordinary close flyby: about 173,000 miles from Earth and just 13,200 miles above the Moon. It is a rare chance to watch planetary science unfold in real time.
- Expected Earth flyby
- About 173,000 miles 278,000 km from Earth's center
- Chance of hitting Moon
- 4.3% → 0% Webb observations now rule out impact
- Estimated size
- 174–220 feet wide 53–67 meters
Field log
Latest observations
47 reports in the archive
How a nearly invisible rock rewired the world’s asteroid playbook
After Webb pinned 2024 YR4 to a Moon‑skimming path, governments and space agencies turned a close call into concrete rules, rehearsals, and new habits.
Read reportGet Ready: How to Watch 2024 YR4 When It Comes Back in 2028
Webb and follow-up work have ruled out impacts — here’s a practical, plain-English plan for amateur…
Read reportFrom a pinprick of light to a century‑long alibi: what Webb and new heat‑models tell us about 2024 YR4
Webb’s razor‑thin detection tightened YR4’s 2032 route; fresh thermophysical work now stretches its…
Read reportYR4’s close shave didn’t end on the sky — it changed how we chase small asteroids
A near‑miss and a daring Webb sighting turned 2024 YR4 from a mystery dot into a live test that…
Read reportWebb's thermal portrait explains why YR4 has a 100‑year alibi — and what scientists will watch next
New thermophysical measurements show YR4 is a fast, rocky 60‑m spinner whose heat signature lets…
Read reportSpin, heat, and a near miss: why YR4’s breakneck rotation changes the ‘what-if’ of a Moon encounter
Webb nailed down 2024 YR4’s Moon‑skim — and its fast spin and high thermal inertia now reshape what…
Read reportYR4’s new portrait: Webb’s follow-up nails down a moon‑skimming pass — and reveals a fast, rocky spinner
Fresh thermophysical measurements show 2024 YR4 is ~61 m across, spins every ~19.5 minutes,…
Read reportTiny Sunlight, Big Consequences: How thermal nudges shape YR4’s 2032 Moon-skim
Webb’s 2026 observations have pinned YR4 to an astonishingly close Moon flyby—now scientists are…
Read report