Supernova Remnants Big and Small

Explanation: What happens after a star explodes? A huge fireball of hot gas shoots out in all directions. When this gas slams into the existing interstellar medium , it heats up so much it glows. Two different supernova remnant s (SNRs) are visible in the featured image, taken at the Oukaïmeden Observatory in Morocco . The blue soccer ball -looking nebula toward the upper left is SNR G179.0+02.6 , which appears to be the smaller one. This supernova , about 11,000 light years distant, detonated about 50,000 years ago. Although composed mostly of hydrogen gas, the blue light is emitted by a trace amount of oxygen . The seemingly larger SNR, dominating the lower right of the frame, is the Spaghetti Nebula, cataloged as Simeis 147 and sh2-240. This supernova, only about 3,000 light years away, exploded about 40,000 years ago. Comparatively, even though they appear different sizes , both supernova remnants are not only roughly the same age, but about the same size, too.