What are the differences between a diffuse/emission nebula and a planetary nebula?
Diffuse nebula Are usually vast concentrations of gas and dust in which stars have been or are being formed. Emission Nebula, Interstellar clouds of hydrogen which glow because of the intense radiation of hot stars inside the nebula. Emission nebulae are typically red. Planetary nebula Is an astronomical object consisting of a glowing shell of gas and plasma formed by certain types of stars at the end of their lives. The name originates from a similarity in appearance to giant planets when viewed through a small optical telescope, and is unrelated to planets of the solar system. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years.
