Does astro means space or stars In the popular TV show The Big Bang Theory Season 3, Episode 4, Sheldon Cooper said that astro means star and Raj said astro means space, I got a little confused here, various websites and others are going 50-50 on the subject. What does astro actually means?

Raj: No, no, no, no! That rate is much too low for what we’d expect from this collision. Do you understand that we’re talking about dark matter colliding in outer space?
Sheldon: Of course I understand. And who are you to tell me about outer space?
Raj: I’m the astrophysicist. Astro means space.
Sheldon: Astro means star.
Astro comes from the greek άστρο which not only means star but has a more general meaning that includes any small dot in the night sky (see https://en.wiktionary.org/wiki/%CE%AC%CF%83%CF%84%CF%81%CE%BF#Greek for details)

In today's language it still has a quite broad meaning:

Oxford English dictionary (https://www.oed.com/view/Entry/12240?isAdvanced=false&amp;result=2&amp;rskey=LlaQB9&amp;): 


  Forming terms relating to stars, other celestial objects, or outer space.


Merriam Webster (https://www.merriam-webster.com/dictionary/astr-)


  : star : heavens : outer space : astronomical 


Conclusion: Sheldon and Raj are right