A Flame Over the Sun

An astonishingly beautiful and rare solar phenomenon, registered by the TESIS telescopes, has been published on the NASA website in the "Image of the Week" section.

The eastern limb of the Sun was lit up as if by fire for almost three days as around ten "blazing" protuberances stretched upwards simultaneously into the solar corona, reaching altitudes of over 100 thousand kilometers. The word "blazing" is not just a beautiful epithet. In this case it characterizes the phenomenon in the best way possible. In both appearance and character these protuberances bear a striking resemblance to tongues of flame bursting upwards from beneath the Sun's surface.

The image is accompanied by the following text:

The great number of protuberances, now observed during a minimum of solar activity, represents one of the riddles, with which TESIS has been faced since its very launch. The substance which makes up protuberances penetrates the corona from below the dense cold layers of the Sun's atmosphere (therefore the temperature of protuberances is always much lower than the temperature of the hot corona, which surrounds them). However, it is quite difficult to raise such great volumes of this substance to altitudes in the hundreds of thousands of kilometers and this requires a significant amount of energy. Therefore, protuberances belong to the class of phenomena associated with high solar activity; the frequency of which should increase as activity levels peak and be considerably reduced at times of solar minimum. Now we see that this is not so.

Large numbers of mass ejections occurring during what is one of the deepest ever minimums in the solar cycle is also unexpected. In April, 2009, there were two consecutive large ejections of matter, connected with the eruption of protuberances, at the lowest point in the Sun's activity. The sources of the energy behind these mass ejections are yet to be discovered.