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Last Post 20 Mar 2019 11:17 AM by  Christina Cohen
Star Color
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Otis 5th Grade

20 Mar 2019 08:44 AM
    We noticed that blue stars are hotter than red stars, how does a star's temperature effect its color? Why are blue stars hotter than red stars?
    Tags: color, star
    >100 Answers
    Posts:113 >100 Answers

    20 Mar 2019 11:17 AM
    Hi Otis,

    That's a great question, particularly since we often refer to things as 'red hot' not 'blue hot'. Any matter that is at a temperature above absolute zero is going to have electrons which vibrate - this vibration creates electromagnetic waves. When these waves are in a certain frequency that our eyes can observe, we see this is visible light is a range of colors, but they can occur with a very wide range of frequencies, portions of which we label as infrared out to ultraviolet, etc.

    The hotter the material is the faster the electrons vibrate and the higher the frequency of the electromagnetic waves they generate. You can visualize this by thinking of holding the end of a piece of rope - if you wiggle that end back and forth you'll see waves move down the rope. If you move the rope end back and forth faster you'll see more waves move down the rope in one second (which is the frequency of the waves) than you do when you wiggle the rope more slowly.

    In the visible portion of the electromagnetic spectrum, lower frequency waves are labeled red and higher frequency waves are labeled blue (that's how the color appears to our eyes). So, blue light means higher frequency waves, which means faster vibrating electrons, which means higher temperatures.

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