Despite popular depictions, the sun is not just a fiery yellow ball in the sky; it is also blue. And purple. And green.
How can the sun produce such a cornucopia of colors? What you see all depends on which wavelength you’re looking through. Using specialized land and space-based telescopes, NASA has created a quilt-like image of the sun bringing representations of many of these wavelengths together in one colorful image. These powerful telescopes can observe rays of light beyond those visible to the naked eye, so colors that seem strange like gray or turquoise make surprising appearances as colors of the sun.
While the sun actually emits light in all colors, this composite image of the sun illustrates the variety of spectrums NASA studies. According to NASA, each snapshot of the composite image contains unique information about the variety of conditions of the sun’s surface and atmosphere.
As Karen C. Fox writes on NASA’s website, “By examining pictures of the sun in a variety of wavelengths – as is done through such telescopes as NASA’s Solar Dynamics Observatory (SDO), NASA’s Solar Terrestrial Relations Observatory (STEREO) and the ESA/NASA Solar and Heliospheric Observatory (SOHO) — scientists can track how particles and heat move through the sun’s atmosphere.”
Our solar system’s bright center is made up of hot gases, so humans can see the sun’s light because it gives off heat. Beyond human fields of vision, however, there’s still more to see: because the sun is composed of a variety of kinds of atoms, it also emits x-rays and extreme ultraviolet light. Each of the different kinds of atoms has a different electrical charge, called an ion. At certain temperatures, each of these ions emanates light at a specific wavelength.
For example, while yellow-green light glows from material at temperatures like the sun’s surface (10,000 degrees F), extreme ultraviolet light is an excellent wavelength to use to study solar flares, which can reach extreme temperatures upwards of 11 million degrees F.
These light emissions are extremely useful for scientists to study the different components of the sun. By using a device known as a spectrograph, scientists can see just how much of each kind of light is in the different materials of the sun. Spectrographs don’t create a visual picture like the composite image, but they do provide data on the various temperature ranges and insight on what’s visible beyond the naked eye.
This composite image reveals the rainbow of colors emanated by the sun’s ions. You can find more information about which ions produce which wavelengths on NASA’s website, where the agency has posted an interactive grid for 13 different wavelengths.