Prominences

A prominence is a dense cloud of incandescent ionized solar gas projecting above the sun's chromosphere into the corona and held in place by the sun's magnetic field. Prominences can last hours and even days.

What the chromosphere lacks in structure, the prominences make up for. Stannyan first described prominences in a letter to Flamsteed following the eclipse of 1706, but the first detailed descriptions of them were by the Swedish astronomer Vassinius at the eclipse of 1733 (although he incorrectly believed them to be lunar in origin). Spanish admiral Ulloa, observing the eclipse of 24 June 1778 from sea, suggested they were caused by sunlight shining through breaks in the moon’s limb, but they were not widely accepted as a solar phenomenon until the eclipse of 1842.

Prominences may be relatively quiescent, persisting for many weeks without significant change, or they may be violently active, erupting outward as far as three million kilometers (two million miles) from the sun’s surface. The more active prominences will exhibit changes from minute to minute; noting any movement or change is a worthy undertaking.

The prominence see here is 40,000 miles long, towering above the sun's surface.