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Homework Help: Supernova's Speed Question

  1. Oct 6, 2004 #1
    For a cretive writing assingment is my class I decided to write a paper called "The Odds of Surviving a Supernova". Needless to say I need to know how long it would take the shockwave to reach earth if our sun supernova'ed. I know that the sun is about 150,000,000,000 kiliometers from earth and that a class 1 supernova travels about 20,000 kilometers per second, I did the basic problem lots of times over and over but always end up with something like is takes 5 years, I know that's not rite so I would like if it I could get a second opionion.

    The equation I came up with 150,000,000,000/1,200,000=12500,
    150,000,000,000=Distnce of Sun to Earth
    1,200,000= 20,000 Kilometers per second converted to Kilometers per hour.

    I just need help understanding the question and what the answers mean. If you would like I could post the paper later to put it into context once I get an answer.

    Any help would be well....helpfull
  2. jcsd
  3. Oct 6, 2004 #2


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    How far is the Sun from the Earth?
  4. Oct 6, 2004 #3

    Chi Meson

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    The problem with your equation is that the number you got for distance is for "meters" not "kilometers." Take off three zeros to get kilometers.


    THe light that is emmitted from the sun at the time of the explosion would consists of ultraviolet, x-ray and gamma rays. THese travel at 300,000 km/s . It would take only 8 minutes for the earth to fry.

    The "shockwave" you are referring to is the "matter" from the sun. MOstly protons, neutrons, alpha particles (helium nuclei), electrons, and an assortment of atoms of nearly every element, all travelling at very high speed, but nothing compared to the speed of light.
  5. Oct 6, 2004 #4

    Chi Meson

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    AND there's another thing:

    Our sun is not the kind that will go bang.

    It can't do a "type 1" because that happens in binary star systems. It can't go "type II" because it's too small.

    It will, however, inflate into a red giant in about 15 billion years or so,and we'll be fried.
  6. Oct 6, 2004 #5


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    There's also neutrinos, especially from a Type II supernova. Of course, billions of those pass through you every day, and you never notice. However, such an intense flood of neutrinos is created in a Type II supernova that you may well notice ... and neutrinos travel at c (or just the tiniest bit below c).
  7. Oct 6, 2004 #6
    Well thanks everyone fro replying to my question, it really helps me a lot.
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