An international research team has made a groundbreaking measurement of the power of jets emitted from the black hole Cygnus X-1, located about 6,000 light years from Earth in the constellation Cygnus. This study confirms a theory proposed by astronomers at the University of Wisconsin–Madison a decade ago. The jets, which stream out perpendicular to the black hole's spinning axis, were observed to travel at approximately 150,000 kilometers per second, or half the speed of light, with a power output equivalent to 10,000 times that of the Sun. Using data from extensive networks of radio telescopes, researchers observed how these jets interacted with the stellar wind from a nearby supergiant star, allowing them to measure the jets' power directly for the first time. Previous estimates of jet power were based on long-term observations that averaged effects over thousands of years, whereas this new measurement reflects the jets' power within just an hour of their emission. The findings, published in the journal Nature Astronomy, provide a crucial understanding of how black holes shape their environment and could lead to new predictions about their influence across the universe.