<ul><li>High-school junior Julian Shapiro has accidentally discovered a black hole 'light echo' twice as wide as the Milky Way while scanning the cosmos for supernova remnants.</li><li>The light echo is a cosmic ghost formed by the ionization of outer regions of gas by a supermassive black hole, which results in an afterglow even after the black hole has quieted down.</li><li>The discovered light echo covers a large area in the sky and is estimated to be about 150,000 to 250,000 light-years in diameter, making it a viable candidate for the largest light echo ever found.</li><li>Black hole researchers are intrigued by this discovery as it can provide valuable insights into the behavior of black holes in the hearts of galaxies.</li></ul>

High-school student accidentally discovers black hole 'light echo' twice as wide as the Milky Way

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