The James Webb Space Telescope has helped scientists determine that asteroid 2024 YR4, which previously had a 4.3% chance of crashing into our moon, will not affect our lunar orbit at all. Instead, it will safely cruise past the moon at an altitude of 13,200 miles (21,200 kilometers).
However, it was quickly found that 2024 YR4 would miss Earth – but it remained unclear if it had hit the Moon instead. Specifically, there was one 4.3% chance that it can hit moon on December 22, 2032 instead. The uncertainty was the result of 2024 YR4’s orbit sun is not known as accurately as necessary to determine with certainty whether it would hit the moon or miss it.
Astronomers thought they would have to wait until 2028 for the next chance to observe 2024 YR4 and refine its orbit before getting any clear answers, but researchers at the Johns Hopkins University Applied Physics Laboratory (JHUAPL) realized there would be a chance for the James Webb Space Telescope (JWST) to observe February 24 YR26. February. this year.
During that week, the asteroid moved toward a faint field of stars whose positions have been precisely measured by the European Space Agency’s Gaia mission. By tracking the object’s motion toward these stars, the The James Webb Space Telescope (JWST) was able to refine its trajectory to high precision. It was no simple measurement; the field of view of the near-infrared camera is only 2.2 square arcminutes, and the asteroid is one of the faintest targets ever observed by JWST.
The scientists at JHUAPL worked with the space telescope’s engineers, along with the European Space Agency’s Near-Earth Object Coordination Center and NASA’s Center for Near-Earth Object Studies, to precisely aim the telescope.
The new measurements mean that the astronomers have now ruled out a collision with the moon. Instead, 2024 YR4 will pass 13,200 miles above the moon’s surface — still a very close encounter, but posing no danger.
Had the impact occurred on the near side of the moon, it would have given scientists their first close-up view of a large impact, and provided a stunning sight for observers on Earth, resulting in a brilliant flash and a new crater about 1 kilometer in diameter. The added energy would have been equivalent to 6 million tonnes of TNT, or basically a large nuclear detonation. Ejecta thrown up by the impact would have mostly rained down on the lunar surface, but millions of pounds of debris would still have escaped the moon’s gravity and fallen toward Earth instead, possibly creating a unique meteor shower that lasted a few days. The debris would also have been a hazard to satellites in Earth orbit, and as some of the debris could remain in Earth’s orbit for years, this hazard would have been long-lasting.
But now that we know that 2024 YR4 will miss its target, we just have to wait for the next asteroid to worry about, and be always on the lookout for any that might threaten Earth.
