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← Will Heat from Our Dying Sun Make Mars Habitable? - Ask the Experts #23

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Showing Revision 3 created 10/17/2015 by Margarida Ferreira.

  1. Hello Space Lab!
    I am Emily Rice,
  2. Professor of Astronomy
    at the College of Staten Island,
  3. and I am here today
    to answer your questions.
  4. The first question is:
  5. If I was able to stand on a neutron star,
  6. would I become extremely dizzy?
  7. What effect would this extreme
    rotational speed have on the body?
  8. Would the neutron star rotate so quickly
  9. that the stars would appear trailed
    as they do in a long exposure photograph?
  10. If you were to stand on a neutron star,
    — which you cant —
  11. but if you were able
    to stand on a neutron star,
  12. you would definitely be extremely dizzy!
  13. Neutron stars rotate at least
    once every few seconds.
  14. And some of them rotate
    thousands of times a second!
  15. This huge rotational speed is definitely
    going to be bad for the body,
  16. but what's worse is the huge gravity
    at the surface of a neutron star.
  17. Because the neutron star,
    is by definition, just a mass of neutrons.
  18. It is just as dense as an atomic nucleus.
  19. It is a huge mass, something that is
    several times more massive than the sun,
  20. condensed into a region that is just
    a handful of miles across.
  21. So the gravity on these things
    would absolutely crush
  22. any person that tried to stand on them.
  23. So if you could stand on the surface
    on a neutron star,
  24. you would absolutely see star trails,
  25. or maybe even just a blur.
  26. Because the human eye
    is only sensitive to changes
  27. at about one tenth of a second or so.
  28. And some of the fastest neutron stars
    rotate thousands of times per second.
  29. So you are literally going around
    hundreds of times
  30. in the time it takes your eye
    and your brain to receive a signal.
  31. And so you would just see a blur.
  32. The second question is:
  33. What is a white dwarf made of
  34. and what is its energy output
    compared to our sun?
  35. (shortly after being formed)
  36. A white dwarf is really a stellar remnant.
  37. It is the corpse of a star
    left over after it explodes.
  38. So the outer layers are blown off
  39. and then the core of the star collapses.
  40. And what's left over
    is the carbon and oxygen,
  41. that was essentially the ash left over
  42. from the hydrogen and helium fusion
    that happened during the star's lifetime.
  43. It's temperature is very very high.
  44. It starts off at about
    10 or 20 thousand degrees Kelvin.
  45. Much hotter than the surface of the Sun.
  46. But these objects
    are still actually very very faint,
  47. because they are so small.
  48. A white dwarf which started out
    about the mass of the Sun,
  49. is now only about the size of the earth.
  50. So it is much more dense than the Sun,
  51. much smaller,
    so much smaller power output,
  52. despite being so hot.
  53. The third question is:
  54. In two billion billion years
    when the Sun starts heating,
  55. will Mars ever become hot enough
    to boil its CO2
  56. and produce
    an atmosphere habitable to life?
  57. So we know that the Sun will get hotter
  58. in a few billion years, if not sooner.
  59. And as Mars gets hotter,
  60. then the CO2 that is frozen
    on the surface right now,
  61. will sublimate into the atmosphere.
  62. It will go directly from the solid state
    into the gas state.
  63. But the Martian atmosphere is already
    over 90% carbon dioxide.
  64. So if we sublimate more carbon dioxide
    from the surface,
  65. into the atmosphere,
  66. it will probably become
    a run-away green house effect,
  67. instead of a nice stable warming
    of the atmosphere.
  68. So chances are, even if Mars
    did become habitable
  69. for life for a little while,
  70. it wont last for very long
  71. and it probably wont be long enough
    to develop life of its own.
  72. Because we think,
    at least for the case of the Earth,
  73. that takes billions of years to happen.
  74. Thanks for your great questions!
  75. If you have a question
    for the next expert,
  76. leave it in the comments below.
  77. The question with the most likes
  78. will be answered in the following round.