NASA's New Horizons probe successfully emerged from the longest hibernation in its nearly two-decade history on 23 June, after spending 321 days in a low-power sleep mode that began in August 2024. The spacecraft, now roughly 9.5 billion kilometres from Earth, is so distant that the signal confirming its revival took nearly nine hours to reach mission controllers via a deep-space antenna near Madrid, Spain. Teams at the Johns Hopkins Applied Physics Laboratory in Maryland report that all systems functioned normally throughout the dormancy period, and scientists will now begin downloading stored scientific data — including readings on solar wind, charged particles, and cosmic dust — as the probe continues its exploration of the outer heliosphere (the vast bubble of solar influence at the boundary between our solar system and interstellar space).