The discovery marks only the second time that an asteroid's impact risk has reached greater than a 1% chance.
© Daniel BambergerThe "risk corridor" (in red) outlines possible places where the newly discovered asteroid might impact, given current observations. Note that the impact chance currently stands at about 1%, and further observations are needed to refine the object's orbit.
Astronomers — professional and amateur alike — have turned their attention to an asteroid with a slight chance of impacting Earth in 2032, based on current observations.
While the possibility is slim, and more observations are needed, the object itself might be large enough to devastate a city, motivating follow-up observations as well as archival searches for pre-discovery observations.The asteroid, designated 2024 YR4, was first noticed on December 27, 2024, by the
Asteroid Terrestrial-impact Last Alert System (ATLAS); searches quickly revealed that ATLAS had already imaged it two days earlier. Then, as observations accumulated, astronomers could roughly determine its orbit. That's when the realization dawned:
The object has some chance of striking Earth.On Monday, January 27th, NASA's Sentry impact-tracking system officially raised the asteroid to a level 3 on the Torino scale. This is only the second time that an asteroid has merited a rating greater than 2 on the
10-point Torino scale, created in 1999 to convey the risk of an impact. At this level, an object has more than 1% chance of striking Earth.
Only one other object, asteroid 99942 Apophis, discovered in 2004, has ever reached that high on the scale. That asteroid peaked at 4, with a possibility of impact in 2029. But additional observations soon ruled that out, sending it back to a Torino rating of 0 — meaning no possible impact within the next century.
The chance of impact for 2024 YR4 is still slim: NASA's Jet Propulsion Laboratory estimates 1.2%. But if it does happen, German astronomer Daniel Bamberger (Northolt Branch Observatories) has used observations in hand to constrain the possible impact in time and location: The impact would take place on December 22, 2032, somewhere along a long line that extends from the Pacific Ocean off the coast of Mexico, through Ecuador and northern South America, across the Atlantic, through central Africa (from Kenya to Somalia), and then across to northern India.
The possible impact track covers big stretches of ocean as well as populated areas and some large cities. "I'd be really excited to see an impact," Bamberger says, "but I don't want it to be this one. Something over Antarctica, please!"
