While in the past, percentages of risk for a dangerous encounter with Earth were measured, the new data from advanced discoveries with NIRCam and MIRI indicate absolute confidence – with unique discoveries in the thermal and structural properties of the asteroid.
While in the past, percentages of risk for a dangerous encounter with Earth were measured in early 2025, the new data from advanced discoveries with NIRCam and MIRI indicate absolute confidence – with unique discoveries in the thermal and structural properties of the asteroid.While in the past, percentages of risk for a dangerous encounter with Earth were measured in early XNUMX, the new data from advanced discoveries with NIRCam and MIRI indicate absolute confidence – with unique discoveries in the thermal and structural properties of the asteroid.
However, the possibility of it hitting the moon has not yet been ruled out.
Webb spots a potential threat
NASA's James Webb Space Telescope recently focused on asteroid 2024 YR4, a near-Earth object that earlier this year was flagged as a potential risk of impact with Earth in 2032. But by the end of February, NASA confirmed that the likelihood of a collision had dropped to near zero.
NASA spoke with Andy Rivkin, the principal investigator in the program that studied the asteroid's properties from observations.
What is important for people to know about these Webb observations?
Earlier this year, asteroid 2024 YR4 was considered a potential threat to Earth in 2032, but in late February it was reported that the chance of a collision had dropped significantly to near zero. However, we would like to use the Webb to measure its properties to understand the nature of asteroids of this size and to gain information about the dangers they could pose to Earth. It is the smallest body the mission has focused on to date, and one of the smallest bodies whose size has been directly measured.
Why did you ask to use theNIRCam (near-Earth camera) and also inMIRI (Medium Range Infrared Imaging Device) in this study? What did you learn from each of them?
Most telescopes study asteroids by measuring sunlight reflected from their surfaces, and it is difficult to accurately determine their size from this information. But at medium-wavelength wavelengths like those used by MIRI, it is possible to measure and use the heat that the asteroids themselves emit to directly obtain the size of the asteroid. The data from NIRCam captures the reflected light, and using it together with the MIRI data gives us not only the size but also the reflectivity of the surface, which is related to the structure of the asteroid.
According to NASA, the chances that 2024 YR4 will hit the country very low. Why are these observations still important?
We are confident that 2024 YR4 will not hit Israel in 2032, but there is still great value in making these observations and analyzing the results. We expect that more potential impactors will be discovered in the coming years as more sensitive asteroid search programs become operational. There is great value in observing with the most powerful telescope we have now. Understanding how best to use it and how to get the most out of its data is something we can do now with 2024 YR4. This will help us determine the best approach to take in a more urgent observation program if another asteroid poses a potential collision threat in the future.
What did you learn? Was there anything surprising in the data?
We found that the thermal properties of 2024 YR4, in other words the rate at which it warms up and cools down, and its temperature at its current distance from the Sun, are unlike what we see in larger asteroids. We think this is probably a combination of its very fast rotation and the lack of fine-grained sand on its surface. We'll need more data to be sure, but it seems consistent with a surface dominated by rocks that are perhaps the size of a fist or larger. And of course, our main goal was to measure the size of 2024 YR4, which we estimate to be about 60 meters. That's about the size of a 15-story building.
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