1d20 Random Moon Finds & Encounters Table For Your Old School Games

 
The hills, a-throng with swarthy pine,
Press up the pale and hollow sky,
And the squat cypresses on high
Reach from the lit horizon-line

They reach, they reach, with gnarlèd hands–
Malignant hags, obscene and dark–
While the red moon, a demons’ ark,
Is borne along the mystic lands.
Moon-Dawn  (1923) 
by Clark Ashton Smith

Random Moon Find Table 1d20

1. This isn't a moon at all but a 20 billion year old battle station from before the big bang! 
2. There are various moon quakes because the "moon" is actually a giant egg & its about to hatch. 
3. There are several ancient inter stellar engines scattered across the face of the moon. This moon is actually an ancient generation ship. 
4. The moon is actually a living biosphere & its growing hungry. 
5. There are at least 5 different species living within the moon & its hollow
6. The moon is an ancient space probe that has settled in this system. Its shut down but if it actives it will tear the system apart 
7. The moon is actually a prop from an old 4 video television show. They left it here 
8. The moon is a bacteria & its hungry. Your PCs are lunch 
9. The moon is the ancient mind of a long dead civilization that is mumbling to itself those who land go mad! 
10. The moon is an ancient Atlantis rocket base. The ships & weapons are still there! 
11. The moon is the home to a roving band of space pirates who are setting up a base & will destroy any witnesses 
12. The moon is the retirement home of a powerful god who will destroy any intruders 
13. The moon is actually a dimensional hole in space. Make a save versus gravity or be sucked in 
14. The moon is wandering the space lanes spawning itself when no one is looking. There are now 2 moons orbiting the planet 
15. The moon is a planetary eater whose surface is actually its shell. This is a 60 hit point creature able to create pseudo pods/mouths to kill & eat all life on the planet below 
16. The moon is the last home to an advanced dying culture that wishes to pass on its secrets. By erasing the PC's minds & implanting their own. 
17. The moon is actually an illusion created by a prankster god from another universe. He's collecting space craft & crews guess whose next! 
18. The moon is the mouth for a strange soul sucking life form & the space craft is next 
19. The moon surface is made from a dairy product & the planets around are actually its children coming in for a meal. 
20. The moon is the home of a space brothel of some legendary qualities also features a casino. Have a nice shore leave!