Goddard Scientific Visualization Studio/SDO/NASA
Coronal rain captured in a solar flare in July 2012.
Yes, it may seem strange, but the truth is that even the Sun “rains”, and the phenomenon has intrigued scientists in recent decades. But now, we know why.
First of all, it is necessary to explain that solar rain does not consist of water drops, as on Earth. Coronal rain occurs in the Sun’s corona, a region of extremely hot plasma that extends above its surface. In the corona, it rains when colder, denser clumps of plasma condense at high altitudes and descend towards the Sun again, explains .
But until now, scientists have been unable to understand how this process could occur so quickly during solar flares. It was assumed based on some models that the distribution of elements in the corona remained constant in space and time, but this is not true.
The mystery was solved by the graduate student Luke Benavitz and by the astronomer Jeffrey Reepfrom the Institute of Astronomy at the University of Hawaii (IfA).
The results, out September 31 in the Astrophysical Journal, show that changes in elemental abundances explain how solar rain forms so quickly.
The discovery allows us to understand “how the Sun works”, researchers say, by helping to anticipate space weather, which affects satellites, communications and electrical grids on Earth. Previous models required heating over hours or days to explain the formation of coronal rain; however, solar flares can occur in just a few minutes.
