The prominences of the Sun are solar filaments of matter projected above its surface and characterizing the activity of the Sun. This activity seems to vary by up to another within a cycle.
In absolute terms, solar activity is regulated by a cycle of an average period of 11.2 years but the duration can vary between 8 and 15 years.
Eruptive prominences of the sun are huge geysers of solar material that take place in the chromosphere and soar to hundreds of thousands of miles in space.

Info: https://www.nasa.gov/content/goddard/what-is-a-solar-prominence