NASA has updated its calculations for asteroid 2024 YR4, increasing the probability of impact with Earth in 2032. The likelihood now stands at 1 in 32, or 3.1%, up from the previous estimate of 1 in 42. While the risk remains relatively low, the steady increase has caught the attention of astronomers and planetary defence experts.
NASA’s Latest Calculations
On 7 February, NASA reassessed asteroid 2024 YR4’s trajectory. Initial calculations put the chance of impact at 1.2%, but that figure quickly rose to 2.3%, then 2.6%, and now 3.1%. The revised probability makes it one of the most concerning near-Earth objects ever recorded.
Read about the past predictions by NASA about the asteroid: 👇
Also Read: NASA Monitors Asteroid Heading Towards Earth: How Likely is Impact?
Asteroid 2024 YR4 was discovered in December 2024. Since then, scientists have been closely monitoring its path. The data comes from 370 observations collected over nearly 55 days.
Figure 2: How the Path of Earth and 2024 YR4 may actually cross [NASASpaceNews/YouTube]
How Big Is Asteroid 2024 YR4?
The asteroid has an estimated diameter of 55 metres—roughly the height of the Leaning Tower of Pisa. While not large enough to cause global destruction, it could still be devastating if it strikes a populated area.
NASA estimates that the energy released upon impact could reach 8 megatons—more than 500 times the power of the Hiroshima bomb. This makes it comparable to the Tunguska event of 1908, where an asteroid explosion flattened 2,000 square kilometres of Siberian forest.
What Are the Chances of Impact?
Despite the increasing probability, scientists stress that asteroid 2024 YR4 is still unlikely to hit Earth. “It is possible that 2024 YR4 will be ruled out as an impact hazard, as has happened with many other objects,” NASA reported.
There is also a small 0.3% chance that the asteroid could hit the Moon instead.
How Dangerous Is This Asteroid?
Scientists use the Torino Scale to measure asteroid risks. The scale ranges from 0 (no threat) to 10 (global catastrophe).
Asteroid 2024 YR4 currently holds a Torino Scale rating of 3. This means it is capable of causing localised destruction and has an impact probability greater than 1%.
Key Details About Asteroid 2024 YR4
Scientists have gathered data from multiple observations over nearly two months. Their calculations estimate the asteroid’s velocity and impact force.
Other key facts:
- Estimated Diameter: 55 metres
- Mass: 220 million kg
- Energy Release:8 megatons
- Impact Probability:1%
- Maximum Torino Scale Rating: 3
- Estimated Speed Upon Impact:32 km/s
Comparison to Past Events
If asteroid 2024 YR4 strikes Earth, its impact could resemble the Tunguska event, which remains one of the largest recorded asteroid explosions in history. That explosion, believed to be caused by a space rock between 50 and 60 metres in diameter, occurred in the Siberian wilderness. Had it hit a city, the devastation would have been catastrophic.
The severity of an impact depends on the asteroid’s composition. A stony asteroid could break apart in the atmosphere, reducing its impact force. A metallic asteroid, however, could strike with full force, triggering an explosion equivalent to multiple nuclear bombs.
How Scientists Refine Asteroid Risk Predictions
Data from the Webb Space Telescope will assist in determining the precise size and trajectory of asteroid 2024 YR4. A comparable case involved asteroid Apophis, which was initially regarded as a potential hazard. Preliminary calculations indicated a slight possibility of impact in 2029, but further observations allowed scientists to dismiss any risk of collision.
A similar process is now underway for 2024 YR4. According to NASA experts, the current 2% risk estimate is not alarming, as further analysis will likely reduce it to zero. This gradual tracking is a routine aspect of asteroid monitoring.
How Asteroid Trajectories Are Predicted
Scientists employ advanced computer models to forecast an asteroid’s future path, considering factors like the gravitational pull of nearby planets and the force exerted by sunlight. While initial calculations may suggest a slight risk, these estimates are refined as more data becomes available. This explains why the 2% impact probability for 2024 YR4 is not a definitive prediction but rather an initial assessment for further analysis.
Many asteroids undergo a similar risk evaluation process. When first identified, they often show a small chance of impact, but in most cases, this risk is eliminated with additional observations.
Asteroids That Were Initially Considered Threats but Later Ruled Harmless
Many asteroids undergo the same risk assessment process as 2024 YR4. When an asteroid is first discovered, astronomers have limited data, and initial calculations sometimes indicate a small possibility of impact. However, as additional observations refine the asteroid’s trajectory, the risk typically decreases to zero.
Notable Asteroids Once Thought to Be Hazardous:
- 2000 SG344: Initially raised concerns due to its trajectory, but further analysis confirmed it poses no threat.
- 2011 AG5: Early studies suggested a potential collision course, yet later calculations ruled it out as harmless.
- Apophis: Once feared to impact Earth in 2029, but as more data became available, scientists ruled out any risk of collision.
Tracking Near-Earth Objects (NEOs)
NASA and global space agencies continuously monitor thousands of near-Earth objects (NEOs), discovering new ones each year. While some initially appear to have a small risk of impact, continued observations and trajectory refinements almost always result in a lower probability or complete elimination of risk.
Although asteroid 2024 YR4 is currently being studied, experts believe its chances of impact will decrease further as additional data is gathered. Nonetheless, astronomers remain vigilant, tracking other asteroids and comets that could potentially pass close to Earth in the future.
Other Asteroids Under Observation:
101955 Bennu:
- Size: Approximately 500 metres in diameter
- Mission: Studied extensively by NASA’s OSIRIS-REx mission, which successfully collected and returned samples to Earth
- Impact Probability: Less than 1% chance of collision in the late 2100s
- Current Status: Continues to be monitored, but does not pose an immediate threat
1950 DA:
- Orbital Period: Extremely long, making future predictions challenging
- Initial Risk Assessment: Early models suggested a small chance of impact in the year 2880
- Updated Findings: Astronomers believe additional tracking will likely rule out any possibility of collision
Are Comets a Greater Threat Than Asteroids?
Unlike asteroids, which generally follow predictable orbits, comets pose additional challenges due to their unstable and elongated trajectories.
Key Differences Between Asteroids and Comets:
- Asteroids:
- Typically originate from the asteroid belt between Mars and Jupiter
- Follow relatively stable orbits
- Easier to track and predict
- Comets:
- Come from the outer Solar System, often the Oort Cloud or Kuiper Belt
- Can experience gravitational shifts, altering their paths unpredictably
- Have volatile surfaces that release gas and dust, which can slightly modify their trajectory over time
Currently, no known comet poses an immediate risk to Earth, but astronomers remain cautious, as new comets can enter the inner Solar System with little warning.
Progress in Planetary Defence
One of the most significant developments in planetary defence is the growing ability to alter the trajectory of potentially hazardous space objects. NASA, the European Space Agency (ESA), and other organisations are working on advanced techniques to deflect asteroids and improve impact prediction models.
Current and Future Defence Strategies:
DART Mission (2022):
- NASA’s Double Asteroid Redirection Test (DART) successfully changed the orbit of an asteroid by deliberately crashing a spacecraft into it.
- This mission proved that human intervention can modify the trajectory of an asteroid, marking a breakthrough in planetary defence.
Future Asteroid Deflection Methods:
- Laser-based deflection: Using concentrated laser beams to vaporise surface material, causing a small push that alters the asteroid’s course.
- Gravitational tugs: Deploying a spacecraft near an asteroid to gradually shift its trajectory using gravitational influence.
- Nuclear-based intervention: In extreme cases, nuclear explosions could be used to either push an asteroid off course or break it into smaller, less dangerous fragments.
With continued technological advancements, scientists can now track thousands of asteroids with increasing accuracy. If a genuine threat were ever detected, there would likely be years or even decades of warning, providing ample time for intervention and risk mitigation.