Animation of a flight towards a planetary nebula. A planetary nebula is a shell of glowing gas cast off a Sun-like star at the end of its life. The expanding shell is illuminated by the hot remnant of the star. They are not related to planets, acquiring the name due to their circular appearance in early telescopes. This nebula is similar to the Helix Nebula, NGC 7293. It is thought that the Sun will produce a nebula similar to this in some five billion years.