SPACE, EXPLAINED SIMPLY
Clouds of gas and dust that trace the birth and death of stars.
01
Nebulae are vast clouds of gas and cosmic dust in interstellar space. Their main gases are hydrogen and helium, yet their material is extraordinarily thin compared with air on Earth.
Their appearance depends on illumination and processes within them. Some glow because nearby stars energise the gas, while others reflect starlight or block it with dark dust.
02
In cold, dense parts of gas clouds, gravity can compress matter until protostars begin to form. These are early stages in the life of future stars.
Dust absorbs visible light, which makes infrared telescopes especially valuable. They can peer into regions where stars are being born.
03
Some nebulae form when a star sheds its outer layers near the end of its life. For a Sun-like star, this glowing gas shell is called a planetary nebula.
Supernova remnants are different: they are expanding clouds of material left after a massive star explodes. Their light and structure contain clues about what happened to the star.