sci-universe:Supernova remnant is a nebula left behind after a supernova, a spectacular explosion in
sci-universe:Supernova remnant is a nebula left behind after a supernova, a spectacular explosion in which a star ejects most of its mass in a violently expanding cloud of debris. At the brightest phase of the explosion, the expanding cloud radiates as much energy in a single day as the Sun has done in the past three million years.(Image credits: ESA/NASA/ESO/Rogelio Andreo) -- source link