As the likelihood of a "city-killer" asteroid striking Earth increased, NASA recently took a "emergency" action. Astronomers are concerned about asteroid 2024 YR4, which was first predicted to have a 1.2% chance of colliding on December 22, 2032, but now has a 2.3% chance.

A potential collision with Earth could cause enormous destruction because the asteroid, which is between 40 and 90 meters (130 and 300 feet) in size, is comparable in size to famous structures like Big Ben or the Statue of Liberty.
International Space Agencies Act

NASA and other space agencies have been given a rare and "emergency" permission to use the James Webb Space Telescope (JWST) to observe and measure the asteroid in order to help determine its precise size and orbit in response to this heightened threat.
A Daily Mail report stated that the 2024 YR4 asteroid could either be 40 or 90 meters across. Improving our size estimate for 2024 YR4 is critical because the hazard represented by a 40-meter asteroid differs significantly from that of a 90-meter one.