A planetary nebula is
A) the spherical cloud of hot gas produced by a supernova explosion.
B) the disk of material in which planets are forming around a star other than the Sun.
C) a shell of ejected gases,glowing by fluorescence caused by ultraviolet light from a hot but dying central star.
D) a gas cloud surrounding a planet after its formation and before the formation of the planet's moons.

Question

Quizplus · Accepted Answer

A planetary nebula is a shell of ejected gases, glowing by fluorescence caused by ultraviolet light from a hot but dying central star. It is formed by a low or intermediate mass star (like our Sun) towards the end of its lifetime, when it has run out of fuel and starts to shed its outer layers. As these layers expand into space, they form a nebula that is typically spherical or elliptical in shape. The central star, which is now a white dwarf, ionizes the gas in the nebula, causing it to glow with different colors.

A Planetary Nebula Is