The Extreme Ultraviolet Imager (EUI) of ESA’s Solar Orbiter mission captured these views of the Sun on 23 February 2021.

The movie begins with a spectacular view of the Sun as seen by EUI’s Full Sun Imager. It shows the transition region of the Sun, at nearly 100 000ºC, which separates the relatively cool chromosphere (the layer above the photosphere, the visible surface of the Sun) from the much hotter corona (the Sun’s outer atmosphere, which extends millions of kilometers into space).

The view then fades to show the low corona of the Sun, which is heated to about 1 million degrees. Zooming in with the High Resolution Imager in extreme ultraviolet light (yellow colours) highlights details of the corona. A sliding side-by-side comparison with the cool solar chromosphere follows, imaged by the Lyman alpha channel of the High Resolution Imager (pink colours).

Finally, zooming in at extreme ultraviolet wavelengths reveals solar campfires, which are the smallest, bright loops in these images. They are likened to miniature solar flares, manifesting as short-lived brightenings in the lower corona, and appear to be rooted in the magnetic flux concentrations of the chromosphere.

Computer simulations replicating the campfires suggests that they may play a role in heating the corona.

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