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Light from the sun .

  1. Aug 12, 2010 #1
    why is the light from the sun a continuous spectrum in the visible range , and of course it emits other frequencies of light . But if the sun is made mostly of Hydrogen and helium ,
    in the nuclear reactions and all the high temperatures in the sun , are we oscillating electrons and protons to get a continuous spectrum .
    obviously the spectral lines of hydrogen and helium and not a continuous spectrum .
    are a bunch of nucleons and electrons flying around that cause a spectrum of light .
  2. jcsd
  3. Aug 12, 2010 #2
    The refraction through our atmosphere is what causes the spectrum, not necessarily the light emitted by the sun directly. Keep in mind that the sun actually puts out a LOT more than we get, but a lot of it (gamma and a lot of UV) gets reflected off our atmosphere. It also puts off heavy amounts of IR (as I recently learned while learning an IR Motion Capture system at my school, making IR capture impossible under sunlight).

    A simple example is to take any kind of light source, such as magnesium burning, which gives a splattered spectrum by itself, and apply different filters to the light to see all of the different combinations of light that you can get.

    A reason why the sun can put out such a strong solid field along the entire spectrum is because of the pure raw amplitude of the light coming in. It refracts off countless atoms in our atmosphere making tons of different lights and still has enough amplitude leftover to burn out your eyes if you stare at it.

    Here's another test you can do: measure the light during mid-day and measure the light during a sunset. You'll notice a huge difference, and that is mainly because the amplitude of the light in a sunset is considerably less than mid-day because of the amount of atoms it has to pass through to get to your eyes.

    So in answer to your question: yes, a ton of stuff is flying around that causes the spectrum of light.
  4. Aug 12, 2010 #3

    D H

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    The atmosphere does absorb some light, particularly outside the visible spectrum. However, the light from the Sun peaks in the visible range and for the most part is a continuous spectrum even when viewed from space. The reason is that sunlight is thermal radiation. The spectrum is fairly close to (but not exactly) the spectrum of a blackbody radiator at 5780 Kelvin. The Sun's spectrum deviates from that of an ideal blackbody radiator primarily due to absorption by atoms in the Sun's atmosphere and due to the fact that temperature inside the Sun increases dramatically with depth.
  5. Aug 12, 2010 #4
    your implying that the sun emits discrete wave-lengths and when the photons hit the atmosphere re-emit a spectrum , i don't think it works that way , When the sun light scatters in the atmosphere they are not absorbed and re-emitted but scattered , The spectrum would have to be emitted from the sun , the white light from the sun gets scattered and broken up when it enters our atmosphere ,
  6. Aug 12, 2010 #5
    so do we get a spectrum from the sun , because we are oscillating protons and electrons in the sun ,
  7. Aug 12, 2010 #6

    D H

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    cragar, I assume your response is to jonathanplumb, not me.

    Suggestion: Good grammar is important in the real world and at this site. Everyone makes a mistake once in a while, but you make several in almost every post you write.
    • Sentences start with a capital letter, end with a period, and are sentences (e.g., subject verb object).
    • The letter after a comma is not normally capitalized.
    • The personal pronoun I is always capitalized.
    • There is no space before a period or a comma.
  8. Aug 12, 2010 #7
    Yes my post was aimed at jon . I'll try to clean up my grammar , but im no English major
  9. Aug 12, 2010 #8


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    Good grammar is a life skill that is critical to a successful professional career and you should practice it here. Most of the mistakes you make appear due to sloppiness/laziness and you don't want to get into those habits, especially since they make you all but impossible to understand. The two sentences above have an incredible six (!) errors.

    The sun emits a nearly continuous spectrum because it glows due to black body radiation. Absorption/emission lines make up a relatively small part of the light we get from the sun.
  10. Aug 12, 2010 #9
    The outer shells largely made of various ions. The nucleons are mostly in the centre regions.
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