From our perspective on Earth, if you (safely) observe the sun it appears yellow and, sometimes, a little reddish. The yellowish appearance of the sun is mainly caused by the way that the atmosphere scatters blue light. Also, yellow is the brightest wavelength the sun emits that can be seen with the naked eye (just take my word for it, don’t go around looking at the sun without proper protection). The sun, in fact, emits light in all wavelengths. When you look at a picture of the sun taken in visible light from space (such as pictures from the Apollo missions, the International Space Station, and other similar projects) the sun will appear white – this is because, without the atmosphere scattering the light, all of the visible colors are seen at the same time; this is known as white light.
While we can learn a lot about the sun by observing it in the visible spectrum, we can greatly expand on that knowledge by observing different wavelengths that are invisible to the human eye. By building specialized telescopes, we can learn about the sun’s composition, activity, and keep a closer and more accurate eye on the sun. Ultimately, this allows us to be better prepared for whatever the sun throws at us.
The images which are pictured were taken by NASA’s Solar Dynamic Observatory (SDO). It uses the Advanced Imaging Assembly (AIA) to observe the wavelengths of different (and specific) molecules as they move around. In addition, the SDO uses the Helioseismic and Magnetic Imager (HMI) which observes the general movements and magnetic properties of the photosphere. Of course, when you’re observing invisible wavelengths of light, or when you’re trying to filter out specific data, you must use false-coloring. And you are left with this…
This picture shows 12 different wavelengths through which we observe the sun. Each wavelength has a specific purpose and a specific usefulness; each reveals a different piece of the puzzle. So, what do they all mean? (In an attempt to direct you to a picture for each explanation, I’ll treat the entire image like a grid starting from the upper-left corner). HMI Dopplergram (grey image, down-2 over-3): This image shows the velocity at which the photosphere (the sun’s surface) is moving.