This image taken with a special solar telescope shows the central star of our solar system, the middle layer of the Sun's atmosphere, the chromosphere. The chromosphere contains singly ionized hydrogen, which produces deep-red photons. Solar telescopes operating in the H-alpha band allow only this one color of the rainbow spectrum to pass through, so that the details of the chromosphere becomes visible. Around the rim of the disc, you can see some gas protrusions, which astronomers call protuberances. Their typical size is 10000-100000 km, that is, even the smallest ones are comparable to the diameter of the Earth. Protuberances are cooler (darker) than the rest of the chromosphere, so when seen in front of the Sun's disk, they appear as dark filaments.
During the recording, an airplane flew just in front of the Sun's disk, its silhouette is clearly visible. Behind it, the obscuration due to the hot gases flowing out of the two engines (this is the same phenomenon as when the objects in the background appear out of focus when looking over a campfire), and the ripples of the two contrails can also be seen.
