Astronomy and Cosmology

3686 topics in this forum

1. Can X-rays be reflected?

   By helium, February 3, 2011
   • 4 replies
   • 6.9k views
   • 
   • lemur
   • February 3, 2011

2. Escape Velocity from the Earth 1 2

   By toruk, December 11, 2010
   • 44 replies
   • 6.8k views
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   • lemur
   • December 17, 2010

3. Only 1 billion years left 1 2 3

   By MaxCathedral, September 25, 2005
   • 51 replies
   • 6.8k views
   • 
   • aj47
   • November 23, 2005

4. The big bang still happening? 1 2 3

   By too-open-minded, October 10, 2013
   • 51 replies
   • 6.8k views
   • 
   • Alan McDougall
   • January 14, 2014

5. Time Is of the Essence!!!! Technology Is Evolving!!! 1 2 3

   By Sostyles, January 30, 2006
   • 60 replies
   • 6.8k views
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   • Sayonara
   • February 9, 2006

6. What Powers Quasars?

   By Airbrush, December 3, 2010
   • 24 replies
   • 6.8k views
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   • insane_alien
   • December 23, 2010

7. black hole+white hole 1 2

   By 6E30306200, July 15, 2005
   • 38 replies
   • 6.8k views
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   • ed84c
   • July 26, 2005

8. Does the universe have "walls"

   By layman77, August 9, 2010
   • 15 replies
   • 6.8k views
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   • CyclOne
   • August 13, 2010

9. Big Bang 1 2 3

   By arvin, March 30, 2007
   • 59 replies
   • 6.7k views
   • 
   • Martin
   • April 19, 2007

10. The search for primitive life. Why? 1 2 3

    By matter, August 4, 2003
    • 70 replies
    • 6.7k views
    • 
    • matter
    • August 17, 2003

11. Is there a way to find out the current Earth-sun distance?

    By Johnny5, April 25, 2005
    • 11 replies
    • 6.7k views
    • 
    • swansont
    • April 27, 2005

12. about expanding of universe 1 2

    By URAIN, July 29, 2011
    • 43 replies
    • 6.7k views
    • 
    • csmyth3025
    • September 13, 2011

13. Does the idea of a "big bang" make any sense? 1 2 3

    By Windevoid, August 20, 2013
    • 57 replies
    • 6.7k views
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    • Airbrush
    • October 22, 2013

14. Where the atoms came from? 1 2

    By needimprovement, August 16, 2010
    • 49 replies
    • 6.6k views
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    • Airbrush
    • September 4, 2010

15. How thick is our spiral arm?

    By Airbrush, June 25, 2013
    • 16 replies
    • 6.6k views
    • 
    • StringJunky
    • June 28, 2013

16. Can there be black holes in a universe of finite age? 1 2 3

    By Rolando, January 22, 2015
    • 74 replies
    • 6.6k views
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    • jeffellis
    • October 14, 2015

17. How was the "big bang" triggered? 1 2 3

    By The dark lord, July 13, 2003
    • 51 replies
    • 6.5k views
    • 
    • Jenab
    • May 21, 2004

18. Does the Oort Cloud protect us?

    By Hypercube, June 16, 2012
    • 24 replies
    • 6.5k views
    • 
    • MarkE
    • June 8, 2018

19. Mapping the universe in "real time"? 1 2 3

    By Baby Astronaut, January 1, 2009
    • 51 replies
    • 6.4k views
    • 
    • Klaynos
    • January 9, 2009

20. Astronomy at Angkor Wat

    By cchea, November 17, 2005
    • 8 replies
    • 6.4k views
    • 
    • cchea
    • November 23, 2005

21. A centre of mass of the Universe. 1 2 3

    By geordief, June 24, 2018
    • 70 replies
    • 6.4k views
    • 
    • Mordred
    • June 27, 2018

22. Why is there so little dust on the surface of the moon?

    By Fanghur, July 10, 2012
    • 11 replies
    • 6.4k views
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    • ACG52
    • September 25, 2012

23. Shen Kuo, 1031-1095 AD, China's Greatest Astronomer?

    By Anaxagoras, July 3, 2007
    • 3 replies
    • 6.4k views
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    • imatfaal
    • March 10, 2011

24. The universe is expanding exponentially 1 2

    By gib65, October 11, 2005
    • 43 replies
    • 6.4k views
    • 
    • mooeypoo
    • January 22, 2010

25. Milky way galaxy mass vs. black hole mass 1 2 3

    By David Levy, January 24, 2015
    • 65 replies
    • 6.3k views
    • 
    • Strange
    • March 14, 2015