Astronomers have identified the most extensive black hole-driven jet system observed to date, designated Porphyrion, extending approximately 7 megaparsecs (Mpc), equivalent to roughly 23 million light-years. This colossal bipolar outflow surpasses previous records, including that of Alcyoneus, and corresponds to the linear extent of about 140 Milky Way galaxies placed end to end.The jets originate from a supermassive black hole residing in a massive elliptical galaxy (approximately 10 times the stellar mass of the Milky Way) located at a redshift corresponding to a luminosity distance of about 7.5 billion light-years. The structure formed during an epoch when the universe was approximately 6.3 billion years old (lookback time ~7.5 Gyr), in an environment where the cosmic mean density was 7–15 times higher than today.Porphyrion exhibits a classical Fanaroff–Riley type II morphology, featuring well-defined lobes, jets, a compact core, an inner hotspot in the southern jet, and an outer southern hotspot potentially associated with backflow. Radio observations at low frequencies (primarily from the LOFAR Two-metre Sky Survey at ~150 MHz, supplemented by uGMRT follow-up and higher-resolution LOFAR data) reveal synchrotron emission from relativistic electrons in magnetized plasma, powered by the central active galactic nucleus (AGN).The kinetic power of the jets is enormous, estimated in the range of 10^{45}–10^{47} erg s^{-1} (trillions to tens of trillions of times the Sun's bolometric luminosity), sufficient to inject vast amounts of energy and magnetic fields into the intergalactic medium (IGM) and the large-scale cosmic web. These outflows extend well beyond the host galaxy's circumgalactic medium, penetrating filaments and potentially reaching void-like regions, where they may heat intergalactic gas, suppress cooling flows, modulate star formation rates in surrounding structures, and contribute to the magnetization of the cosmic web on megaparsec scales.The discovery, based on systematic analysis of LOFAR data (which has cataloged over 10,000 extended radio sources, including numerous giant jet systems), demonstrates that such extreme jet lengths are not exceedingly rare and that relativistic jets can maintain remarkable coherence and collimation over cosmological distances and through denser early-universe environments, defying expectations from magnetohydrodynamical instability models.This finding implies a more significant role for AGN feedback via giant jets in regulating galaxy evolution, baryon cycling, and the thermal/magnetic properties of the IGM during the peak epoch of black hole growth and cosmic structure formation.Reference: Oei, M. S. S. L. et al. Black hole jets on the scale of the cosmic web. Nature 633, 320–326