Titan is the largest of Saturns many moons where Beth along her children, Summer and Morty, was imprisoned. It appeared briefly in a memory in Morty's Mind Blowers.
At some point, probably shortly after Jerry and Beth's divorce, an evil Alien kidnapped Beth, Summer and Morty, and he brought mother, daughter and son to this moon, on a mountain, he tied and gagged the two siblings and locked them in two pointed spheres, while Beth was tied up and seated on a throne, the Alien made a proposal to the woman, making choose to Beth which one of her two children should survive and who should die, knowing that children are everything for a mother, while the boy and the girl were trapped in the spheres. Beth promptly chose her daughter Summer, much to her son Morty's disbelief, just before the arrival of Rick by a portal. After shooting the Alien, Rick explained that he confused Titan with Phoebe, another moon of Saturn, and later, he freed his daughter and grandchildren.