Red Giant
From Slackerpedia Galactica
A red giant is a star that is red and can be up to 10 times the mass of the Sun and are known to strip superheroes of their powers. Betelgeuse is a notable red giant in the constellation of Orion.
A red giant is an intermediate mass star near the end of its life. As a star fuses Hydrogen it creates Helium, which settles in the core. Eventually the temperature gets warm enough for the Helium to fuse, creating Carbon (among other things). This new burning of Helium creates extra pressure that puffs out the outer, mostly Hydrogen, layers of the star. The star swells up and the outer layers become less dense and cool somewhat, turning the star into a red giant. If the star is massive enough, it will later turn into a red supergiant - which is basically the same thing, only bigger.
(Not to be confused with the Jolly Green Giant.)
Most red giants become Mira class variable stars at some point, pulsating back and forth with a frequency on the order of months to years. Eventually they shed these outer layers and create beautiful nebulae.
Our own Sun will likely become a red giant in about 4 billion years. It will certainly engulf Mercury and Venus. It is debatable whether it will engulf the Earth or not. But even if the Earth escapes, the planet will be scorched dry and the newly red Sun will take up the entire sky in the daytime.
