- 1708 - My New Year’s Resolution. The colors in astronomy. This review explains how astronomers gets those beautiful color pictures of nebulae.
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----------------- 1708 - My New Year’s Resolution. The colors in astronomy.
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- I have a confession to make. All those beautiful astronomy pictures I have been attaching to my reviews, they are not real, they use “ false colors” to make the picture look beautiful. If you were looking out the window of your space ship those beautiful nebulae would be a mixed reddish color, or blurry gray.
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- Hydrogen atom emissions are red, 656.3 nanometers wavelength, and, there is so much hydrogen gas in the nebulae it would swamp out any other colors that were there . And, even then the light intensity must be high enough for you to see colors, otherwise your eyes only see gray.
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- So, what do astronomers do to fake these pictures?
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- They use filters to separate the wavelengths out of the gray - white light. Take a gray image. Reflect it off a diffraction grating to separate the wavelengths. The diffraction grating is simply etched glass, or plastic, with closely spaced lines. You can see diffraction grating by looking at the CD or DVD in the light. Witness the rainbow of colors coming from the reflection. That is a rainbow of different wavelengths of light.
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- One filter in the telescope would pick out the red hydrogen gas color - wavelength. A second filter would pick out the green oxygen gas color. A third filter would pick our the pink sulfur emissions color.
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- Now, you put these separate pictures on a CCD, digital camera. Upload it to a computer . Now assign any “ false color” you want to each of the separate images. Play around until you make the cover of Astronomy Magazine. Now you know the truth. I feel much better.
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- Where do colors come from? Colors are a special part of the light spectrum, the visible part of the full electromagnetic spectrum that occupies 400 nanometers to 700 nanometers wavelengths.. Each individual color depends on the individual wavelength. Cones in your eyeball match the size of these wavelengths. The light emissions come from the atoms of the elements. Atoms are different because they have a different number of protons in their nucleus matching the same number of electrons orbiting the nucleus.
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- The electrons occupy different energy levels as they orbit the nucleus. in order to jump from a higher to lower energy level the electron must emit that specific amount of energy. Each change requires that specific amount of energy. Energy comes in bundles called photons.
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----------------------- Photon Energy = h * c / w
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---------------------- Photon Energy = 6.626 *10^-34 Joules * Seconds * 3 * 10^8 meters / second // the wavelength.
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- Planck’s Constant, “h”, and the speed of light, “c”, are constants. So , energy is inversely proportional to the wavelength. The shorter the wavelength the greater the energy. Blue light contains more energy than red light. Ultraviolet contains more energy than infrared.
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- The hydrogen atom emits blue light at 486.1 nanometers wavelength when the electron jumps from energy level 4 to energy level 2. The electrons emits red light at 656.3 nanometers wavelength when the electron jumps from energy level 3 to energy level 2. Blue light carries more energy than red light because it had to jump further crossing more energy levels.
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- It is not really cheating. It is more use of artistic license in the name of science. Or, maybe astronomical use of educational license.
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- Sorry to break it to you, but, the Hubble Space Telescope can not even take color pictures. In fact, your eye, as wondrous of an instrument as it is, cannot distinguish any colors if the light intensity is at too low a level. The eye has a problem seeing colors especially at the edges of the visible spectrum, the blue edge, or the crimson edge. So, we just “enhance” the image for you, thanks to the power of filters and computers.
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- A single photon is a small bundle of energy. Here is the energy of blue light at 486.1 nanometers wavelength:
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----------------------- E = h * c / w
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---------------------- E = 6.626*10^-34 joule * sec * 3 *10^8 m/sec // 486.1*10^-9 m
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----------------------- E = 4.08 *10^-19 Joules
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- The energy of a photon of blue light is 0.000,000,000,000,000,000,408 Joules
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- A 100 watt light bulb puts out 100 Joules per second in photon energy. Sorry, for deceiving you about the beautiful images in astronomy. But, it is for our own good. It is not enough to have the best product, you have to have good marketing as well. Stay tuned for more revelations in astronomy.
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RSVP, with comments, suggestions, corrections. Index of reviews available ---
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