1. 宇宙   orbit   universe   astronomer   astronaut   Hint Half-n-half Clue   2. 太陽系   solar system   asteroid   orbit   telescope   Half-n-half Clue   3. 太陽   asteroid   astronomer   satellite   Sun   Half-n-half Clue   4. 銀河系   solar system   star   galaxy   universe   Half-n-half Clue   5. 重力   telescope   gravity   Earth   moon   Half-n-half Clue   6. 宇宙飛行士   planet   orbit   gravity   astronaut   Half-n-half Clue   7. 彗星   Earth   universe   comet   solar system   Half-n-half Clue