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Asteroid 2024 YR4, initially considered a potential threat, has been re-evaluated by scientists using the James Webb Space Telescope (JWST). Observations indicate the space rock is larger than previously estimated, prompting further analysis of its trajectory and potential impact, primarily concerning the moon rather than Earth. Space agencies continue to monitor near-Earth objects, refining their understanding of potential risks.
Updated Assessment of Asteroid 2024 YR4 Size
Astronomers have released updated findings regarding asteroid 2024 YR4, also referred to as the ‘city-destroying’ asteroid in earlier reports. Utilizing the advanced James Webb Space Telescope (JWST), experts have determined that the asteroid’s dimensions exceed previous calculations.
Initial Size Estimates Recalibrated
Initial assessments, based on ground-based observations, suggested asteroid 2024 YR4 measured approximately 40 meters (131 feet) in diameter. These preliminary figures were derived from indirect measurements.
JWST Direct Measurements Reveal Larger Dimensions
However, direct measurements obtained by the JWST indicate a revised diameter of 60 meters (200 feet). This updated figure signifies that the asteroid is roughly the height of a 15-story building, a notable increase from earlier estimates.
Potential Impact Force of Asteroid 2024 YR4
An asteroid of this size impacting Earth would generate a substantial explosion. Calculations suggest an impact would unleash energy equivalent to 500 times the power of the atomic weapon detonated over Hiroshima, underscoring the potential destructive capacity of such an object.
Initial Impact Probability and Refinement
Following its discovery in December of the previous year, the calculated probability of asteroid 2024 YR4 impacting Earth rose to a concerning 3.1 percent. This percentage represented the highest recorded likelihood of impact for a sizable asteroid at that time.
Earth Impact Risk Mitigated, Moon Remains a Focus
While space agencies like NASA have since dismissed the possibility of 2024 YR4 striking Earth, observations from the JWST highlight a potential risk to the moon. Current data indicates a nearly four percent probability of collision with Earth’s natural satellite.
Timeline of Assessment and Observation
In February, global space agencies issued warnings regarding a potential Earth impact on December 22, 2032. Although many anticipated the impact probability to decrease as predictions became more refined, the initial assessment necessitated enhanced observational data.
Urgent JWST Observation Program
During this period of uncertainty, NASA authorized an ‘urgent’ observation program, granting access to the JWST for an international team of astronomers. Their objective was to precisely determine the size of the approaching asteroid, crucial for evaluating the potential consequences of an impact.
Limitations of Ground-Based Telescopes
Size estimations from Earth-based telescopes, while valuable, were considered approximate. These estimations relied on the reflection of light from the asteroid’s surface, a method prone to inaccuracies due to varying surface reflectivity.
As the European Space Agency explained, asteroid brightness is an indicator of size, but this correlation is influenced by the asteroid’s surface reflectivity.
JWST Infrared Measurement Technique
To overcome these limitations, the JWST employed an instrument specifically designed to measure infrared radiation, the heat emitted by the asteroid. This method provides a more accurate size determination, independent of surface reflectivity.
On March 26, the JWST observed asteroid 2024 YR4 for a five-hour duration, tracking its rotation through space.
Data Analysis and Asteroid Characteristics
The infrared data collected revealed asteroid 2024 YR4 to be 60 meters in diameter, with a margin of error of plus or minus seven meters. The data also indicated a rotation period of once every 20 minutes.
Implications for Planetary Defense Planning
At this confirmed size, if 2024 YR4 were still considered an Earth impact threat, it would have triggered protocols from the United Nations-backed Space Mission Planning Advisory Group. This body would evaluate the necessity of asteroid deflection strategies to prevent a potentially devastating impact.
Insights into Asteroid Composition
Dr. Andy Rivkin, an astronomer from Johns Hopkins University and principal investigator for the JWST program, emphasized the improved understanding gained about the asteroid’s nature.
“We observed that the thermal properties of 2024 YR4, its heating and cooling rates, and temperature at its solar distance, differ from larger asteroids,” Dr. Rivkin noted.
“This likely results from a combination of rapid spin and a lack of fine-grained dust on its surface. Further data is needed for definitive conclusions, but current observations suggest a surface dominated by larger rocks.”
Future Planetary Defense and Lunar Impact Scenario
While the probability of Earth impact remains negligible, the ability to effectively observe potentially hazardous objects is crucial for future planetary defense. Understanding asteroid characteristics through advanced telescopes like JWST is invaluable.
Dr. Rivkin stated, “We anticipate discovering more potential impactors as asteroid search programs become more sophisticated. Utilizing our most powerful telescope is essential.”
“Learning optimal utilization methods and maximizing data extraction now, with 2024 YR4, is beneficial.”
Scientific Gains from Potential Lunar Impact
Should 2024 YR4 impact the moon in 2032, the event could offer significant scientific benefits. Knowing the precise size and composition of the asteroid would be invaluable for researchers globally.
While a lunar impact would not affect Earth, it would provide an unprecedented opportunity for scientists to observe a crater forming in real-time on the moon’s surface.
Data gathered from such an impact could enhance our understanding of lunar crater formation and surface properties.