NASA activates planetary defense for comet 3I Atlas due to its unusual composition

NASA activated its planetary defense protocol for the first time for an interstellar object, comet 3I Atlas, due to its unprecedented composition and behavior. The comet, discovered in July 2025, is rich in nickel but lacks iron, and exhibits an unusual anti-tail phenomenon, prompting scientific investigation. Despite its distant trajectory, the comet's anomalies have led to its classification as a priority case by the International Asteroid Warning Network.