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Q:
I teach general science and I suppose I should know the answer to this question. I have some good ideas but would like a clear explanation for the kids.
1) How can you tell if the ’color’ a star is due to its temperature or whether it is going to or away from the earth?
2) How exactly do they tell the temperature of the sun and the corona?
Thanks in advance
Frank C. Vovk
- Frank C. Vovk (age 32)
Hartford High, Hartford KS, USA
A:
Well, the color of stars that we see is due to the stars' temperature.
Motion toward or away from us creates a very small shift and really
does not change the color for any stars that we can see. (We can see
far away galaxies that have very large color shifts, but we can't pick
out individual stars in them since they're so far away).
Scientists
can find the temperature of the sun by looking at the colors in the
light it emits (the spectra). This is the same principle that would
allow you to measure the temperature of a burner on your stove by
looking at the color it was glowing, or even more familiar, to measure
someones body temperature by using an infrared ear thermometer. For the
corona, you can get a spectra by blocking out the light from the rest
of the sun with a black disk placed in front of your telescope. (Or you
can wait for a total solar eclipse!) This allows you to see the faint,
wispy corona and take a spectra of just this area.
For more information, check out
The Stellar Sun especially the part about Stellar Fingerprinting.
LC, GB
(published on 10/22/2007)
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