Seven Cosmic Rumors

Might as well try to write something.

• Illithids once had an empire that spanned worlds. Why have they degenerated and devolved into a handful of enclaves deep within the earth? Because the dead god on which the Githyanki built their astral capital is Ilsensine, their patron. What the Githyanki don't know is that sooner or later Ilsensine is going to stop playing possum.
• It's easier to get to the Astral Plane from the elemental planes of water and air than the planes of fire and earth. Water and Air elementals are known to brag about this in mixed company.
• It's said that there's one location in the world that is a natural gate to each outer plane. Mount Celestia is a particularly tall mountain range on which an order of Lawful Good monks live forever in pursuit of spiritual alignment, the Abyss is a massive gorge shrouded in scalding-hot steam and noxious vapors, Mechanus is an elaborate space station that has sat in orbit since time beyond memory, and so on and so forth. Regardless, all are hopelessly remote and it would be a fool's errand to try to journey to them... unless one were a great hero.
• The best way to get to the Moon is by ethereal travel. Somehow it manages to be the one part of the Ethereal that's really scenic. The moon itself is ethereal stone and exists equally in both planes.
• Ilepho, a gnome philosopher, once wrote that the Feywild and the Shadowfell are not separate planes unto themselves, but that the material plane, like many outer planes, has overlapping layers (if you must know, he compared it to a Spanakopita). His half-sister Argia the Elder disagreed, she wrote that the Feywild is the ancient, mythic past and the Shadowfell is the aftermath of some future catastrophe yet to be seen. Their disagreement culminated into a duel to the death.
• The stars are roughly divided (in increasing order of frequency) between being the distant suns of other worlds, holes in the dome of the sky through which the radiance of distant planes leaks, the eyes of unfathomable entities that coolly and enviously regard the earth, and ordinary rocks with Continual Light spells cast upon them that slipped the surly bonds of earth to float in the sky. Depending on who you ask, this list might be in a different order.
• There used to be other elemental planes. No one has seen them in centuries.