ABC Game

yearbooks, yells (cheering, not teachers), youngsters

New topic: things in space: stars, planets and species (real or imagined), space ships, constellations

Alpha Centauri (closest real star to our solar system)

Andoria and Andorians (planet and species in Star Trek universe)

Alderaan (Princess Leia's home planet, in Star Wars universe)

Andromeda (constellation: the chained lady or the Princess)

Aquarius (constellation: the water-bearer)

Aries (constellation: the ram)

I hope that's enough flexibility for an interesting topic

Caprica (planet on Battlestar Galactica)

Earth

Evening sky

Galaxies of all sorts!

Gas giant planets

Gemini, a constellation

Gemini, the second manned NASA space program (conducted between projects Mercury and Apollo)

Gravity, which holds it all together.

interstellar

Ionosphere

International Space Station

stuck ????

Mars, moon, Mecury

oops!

Neptune, Nebula, Night Sky

photopshere, planet, phases, Pluto (which is still a planet to me )

rocket, radiation,

Tantalus – A Federation prison colony is located on planet Tantulus, where the warden conducted cruel psychological experiments on the inmates in Star Trek (TOS).

Talax/Talaxian - Neelix from Star Trek: Voyager is from planet Talax in the Delta Quadrant and his people are Talaxians

Tatooine is the home planet of Luke Skywalker in Star Wars

Takodana is a Forest planet in The Force Awakens

Taurus, Triangulum, and Tucana are constellations

Terrestrial   

(not going there, trying to be mature, aww to heck with it, roflol)

Venus

Virgo (constellation)

zenith and zodiac

I'll let someone else pick next topic

I picked the last topic: things in space: stars, planets and species (real or imagined), space ships, constellations; many of which are very big

New topic: things that are small

amoeba, atom

edited to improve clarity (I hope)