At first glance it may seem that it is the same every day, but the Sun "changes face" constantly. The European Space Agency (ESA) has demonstrated in detail how it does it with a striking montage of the star in 365 images, one for each day of 2018.
The photographs were taken by the SWAP camera of the ESA Proba-2 satellite and grouped in a succession that shows, as I did in previous years, the changes that go unnoticed by the human eye.
The camera used works at extreme ultraviolet wavelengths to capture the hot and turbulent atmosphere of the Sun, the corona, with temperatures of about one million degrees, according to the European agency in a statement. This satellite Monitors the Sun continuously.
The Sun usually follows a cycle of 11 years of activity and during 2018 reached its solar minimum, so it showed few active regions, which appear brighter in the images.
One way to assess the level of activity is to count the sunspots (dark spots in the images) or record the power of the flares. The most energetic eruption of 2018 was recorded on February 7 in a small region located in the central latitudes of the eastern hemisphere of the Sun (to the left of the center of the Sun in the corresponding image).
The most powerful flares, along with coronal mass ejections that eject gigantic clouds of solar material into space, can generate such radiation emissions that, if pointed directly at the Earth, could create geomagnetic storms capable of interrupting our communications systems and electrical networks, as well as causing damage to satellites, explains ESA.
On the other hand, the moments of low solar activity are useful to study the evolution of the active regions without the difficulty that supposes the superposition and interaction between regions. Active regions can last for days or even months, and you can see how they rotate and traverse the face of the Sun repeatedly.