From ESA:

This otherworldly, ever-changing landscape is what the Sun looks like up close. ESA’s Solar Orbiter filmed the transition from the Sun’s lower atmosphere to the much hotter outer corona. The hair-like structures are made of charged gas (plasma), following magnetic field lines emerging from the Sun’s interior.

The brightest regions are around one million degrees Celsius, while cooler material looks dark as it absorbs radiation.

This video was recorded on 27 September 2023 by the Extreme Ultraviolet Imager (EUI) instrument on Solar Orbiter. At the time, the spacecraft was at roughly a third of the Earth’s distance from the Sun, heading for a closest approach of 43 million km on 7 October.

[ESA]