1. 地球   astronaut   orbit   telescope   Earth   Hint Half-n-half Clue   2. 轨道   orbit   meteorite   planet   universe   Half-n-half Clue   3. 飞星   meteor   outer space   satellite   atmosphere   Half-n-half Clue   4. 星系   moon   atmosphere   galaxy   Sun   Half-n-half Clue   5. 重力   gravity   atmosphere   orbit   universe   Half-n-half Clue   6. 宇宙   satellite   universe   planet   comet   Half-n-half Clue   7. 光年   asteroid   Earth   atmosphere   light years   Half-n-half Clue