When a massive star explodes, it hurls giant clouds of gas into space. These clouds, known as supernova remnants, can stretch across hundreds of trillions of kilometers. Two such clouds — G107.7-5.1 and G150.3+4.5—were recently studied by astronomers using a telescope in Turkey. They split the light from these clouds into colors, much as a prism splits white light into a rainbow.

It turned out that in both clouds, the gas glows due to shock waves. These waves, like invisible hammers, compress and heat the gas, causing it to emit light. The speed of such waves exceeds 100 kilometers per second — about 300 times faster than the speed of sound in air. The astronomers also noticed that the clouds contain dust that partially blocks the light, like fog obscuring streetlights.

The two clouds turned out to be surprisingly similar. This suggests they formed from similar explosions. Such studies help us understand how stars die and how their remnants affect the surrounding cosmos.