"red giant." YourDictionary, n.d. Web. 18 December 2018. <https://www.yourdictionary.com/red-giant>.
red giant. (n.d.). Retrieved December 18th, 2018, from https://www.yourdictionary.com/red-giant
A giant star that has a relatively low surface temperature, giving it a reddish or orange hue. Red giants are non-main-sequence stars positioned in the upper right of the Hertzsprung-Russell diagram. They are not massive stars but rather late, expanded stages of lower-mass main-sequence stars that have exhausted the hydrogen in their core and are fusing their remaining hydrogen into helium in a luminous outer shell. The Sun is expected to become a red giant in about 5 billion years, expanding to 70 times its current size and bringing its surface extremely close to Earth's present orbit.