2024 YR4
Key facts
- What it is
- Small near-Earth asteroid (Apollo group)
- Size
- About 60 m across
- Discovered
- 2024, by the ATLAS survey in Chile
- Spacecraft
- Not yet visited
- Orbit group
- Apollo
- Average distance from the Sun
- 2.52 au (about 380 million km)
- Time to go round the Sun
- 4 years
- Closest and farthest from the Sun
- 0.85 to 4.18 au
- Tilt of its orbit
- 3.4°
- Closest its orbit comes to Earth's
- 410,000 km (1.1 times the Moon's distance)
An au (astronomical unit) is Earth's average distance from the Sun, about 150 million km. Orbit figures are from open tracking data, figures last updated 1 Nov 2026.
2024 YR4 is a small asteroid that briefly became the most talked-about rock in the sky, and its story is a perfect lesson in how asteroid tracking works. It was discovered on 27 December 2024 by an ATLAS survey telescope in Chile, shortly after it had passed Earth.
As astronomers measured its path over the following weeks, the calculated chance that it could hit Earth on 22 December 2032 rose, peaking at about 3 per cent in February 2025. That was the highest figure ever recorded for an asteroid of its size, and it was widely reported. Then, as more observations came in, the chance dropped quickly to practically zero. Earth is not at risk.
Why did the chance rise and then fall? When an asteroid is first found, its orbit is uncertain, so scientists calculate a whole cloud of possible positions for it in the future. If Earth lies inside that cloud, there is a chance of impact. As each new measurement shrinks the cloud, the chance can go up for a while, simply because the cloud gets smaller while Earth is still inside it, until the cloud shrinks enough to slide off Earth altogether. That is what usually happens, and it happened here.
The James Webb Space Telescope measured its size in 2025 at about 60 metres. For a time there remained a small chance that it might hit the Moon in 2032, but further observations by the same telescope in February 2026 ruled that out too. It will pass the Moon at a safe distance.
The episode showed the system working exactly as it should: an object found early, tracked carefully, and cleared calmly.
Coming close to Earth
Its next passes within about 30 million km of Earth, worked out from its orbit. Each one is a safe miss.
| Date | Distance | In Moon distances |
|---|---|---|
| 17 Dec 2028 | 8,000,000 km | 21 |
| 22 Dec 2032 | 280,000 km | 0.7 |
| 5 Jan 2052 | 25,000,000 km | 66 |