Introduction

Asteroid 2024 YR4 is a near-Earth asteroid, meaning it is an asteroid in an orbit that brings it into Earth’s region of the solar system. When it was first discovered, it appeared to have a very small chance to impact Earth on Dec. 22, 2032. As observations of 2024 YR4 continued through early 2025, NASA concluded the object poses no significant impact risk to Earth in 2032 and beyond.

New infrared observations from NASA’s James Webb Space Telescope have decreased the uncertainty of the asteroid’s size, and 2024 YR4 is now estimated to be 174-220 feet (53-67 meters), about the size of a 10-story building. The previous size estimate of 131-295 feet (40-90 meters) was derived from visible light measurements from ground-based telescopes. 

This object is of particular interest for planetary defense for two reasons: 1) it is large enough to cause localized damage in the unlikely event that it should impact Earth, and 2) it surpassed the 1% impact probability threshold to warrant formal notification of the object to other U.S. government agencies involved in planetary defense as well as to the Space Mission Planning Advisory Group and to the United Nations Office of Outer Space Affairs per the International Asteroid Warning Network’s notification charter.

As more observations of the asteroid’s orbit were obtained, its impact probability became better known and enabled planetary defense experts to determine it poses no significant risk to the planet.  The latest data on all known asteroids that NASA is tracking that could pose an impact hazard to Earth will continue to be made available via NASA’s automated Sentry page.

Discovery

2024 YR4 was first reported to the Minor Planet Center – the international clearing house for small body positional measurements – by the NASA-funded Asteroid Terrestrial-impact Last Alert System (ATLAS) in Chile on Dec. 27, 2024. ATLAS comprises several telescopes around the world and is managed by the University of Hawaii’s Institute for Astronomy.

How Big is the Asteroid?

Based on infrared observations from NASA’s James Webb Space Telescope made in March 2025, asteroid 2024 YR4 is now estimated to be 174-220 feet (53-67 meters).

Will Asteroid 2024 YR4 Impact Earth?  

When first discovered, asteroid 2024 YR4 appeared to have a very small chance of impacting Earth on Dec. 22, 2032. However, as more observations of the asteroid were collected, and as that data was added to its orbit calculations, 2024 YR4 was deemed to have no significant chance of Earth impact in 2032 and beyond.  

How Much Damage Would an Asteroid of This Size Cause If It Impacted Earth?  

The damage caused by an impacting asteroid depends greatly on the exact size and composition of the asteroid. The exact size of 2024 YR4 is still uncertain, but an airburst is a likely scenario for its size range. If the asteroid were to enter the atmosphere over the ocean, models indicate that airbursting objects of this size would be unlikely to cause significant tsunami, either from the middle of the ocean or even nearer shore.

If the asteroid entered the atmosphere over a populated region, an airburst of an object on the smaller side of the size range, about 130 - 200 feet (40 - 60 meters) could shatter windows or cause minor structural damage across a city. An asteroid about 300 feet (90 meters) in size, which is much less likely, could cause more severe damage, potentially collapsing residential structures across a city and shattering windows across larger regions. 

How Does NASA Determine the Impact Probability of Asteroids?  

NASA’s Near-Earth Object Observations program funds observatories to search for undiscovered asteroids and track existing potentially hazardous asteroids. Using the observation data, NASA teams calculate and refine near-Earth object orbits using computer models. Once the orbit of an asteroid is computed, these same computer models at NASA’s Center for Near-Earth Object Studies can project how close the asteroid might approach Earth over the coming years and decades.

Why Does the Impact Probability Change so Frequently? Where Can I See the Latest Impact Probability?

This is the scientific process. As NASA and others involved in the International Asteroid Warning Network gather more observations of asteroid 2024 YR4, the asteroid’s future trajectory can be better understood. This is an opportunity to observe the science of planetary defense in action. As new tracking data becomes available and new probability assessments are made, these results will be posted on the Sentry risk list page.

Is it Possible to Deflect Asteroid 2024 YR4? Could We Use a Spacecraft Similar to DART?  

A kinetic impactor spacecraft like NASA’s Double Asteroid Redirection Test (DART) mission is one asteroid deflection technique that could be used to address a potentially hazardous asteroid in the future. Each asteroid is unique, and deflection would depend on the asteroid’s size, physical properties, orbit, and discovery warning time. 2024 YR4 poses no significant impact risk to the planet, and thus it is premature to speculate on potential deflection techniques for this asteroid.

Is it Possible 2024 YR4 Could Impact the Moon?

Asteroid 2024 YR4 has a very small chance of impacting the Moon on Dec. 22, 2032. If the asteroid were to impact the Moon, it would not alter its orbit.