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
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 sunís 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.