- Great A’Tuin is the Giant Star Turtle (of the fictional species Chelys galactica) who travels through the Discworld universe’s space, carrying four giant elephants (named Berilia, Tubul, Great T’Phon, and Jerakeen) who in turn carry the Discworld. The narration has described A’Tuin as “the only turtle ever to feature on the Hertzsprung–Russell diagram”.
- Ring Nebula (Wikipedia)
The Ring Nebula (also catalogued as Messier 57, M57 and NGC 6720) is a planetary nebula in the northern constellation of Lyra. Such a nebula is formed when a star, during the last stages of its evolution before becoming a white dwarf, expels a vast luminous envelope of ionized gas into the surrounding interstellar space.