Credit: ESOAstronomers witness 'sudden awakening' of massive black hole in far-away galaxy.The cosmic event was first spotted in 2019 when a US telescope detected an "unusual brightness" around 300 million light-years away.Data showed the "calm" galaxy in the constellation Virgo had mysteriously started to glow.

Credit: ESOAstronomers witness 'sudden awakening' of massive black hole in far-away galaxy.The cosmic event was first spotted in 2019 when a US telescope detected an "unusual brightness" around 300 million light-years away.Data showed the "calm" galaxy in the constellation Virgo had mysteriously started to glow.