prominences

Prominences are notable features that appear extended beyond their surroundings in various scientific disciplines. The most common uses refer to topographic prominence in geography and geology, and solar prominences in astronomy.

Topographic prominence measures a summit's independent height. It equals the vertical distance between the summit and the lowest saddle that encircles the peak and no higher summit. The calculation requires identifying this key saddle and a higher neighbor; the resulting value explains how distinct the peak appears in the landscape. Prominence is used to rank mountains and to define significant summits in many lists.

Solar prominences are large, bright features that extend outward from the Sun's surface, anchored in the photosphere and extending into the corona. They consist of relatively cool, dense plasma supported by magnetic fields and are best seen in specific spectral lines, such as hydrogen-alpha. Prominences come in quiescent types, which are stable for days, and active-region types, linked to sunspot activity. They can last for days to weeks and may erupt, releasing material into space as part of coronal mass ejections. When observed against the solar disk, they appear as dark filaments; at the limb, they appear as bright, looping structures.

Prominences thus describe extended structures shaped by gravity and pressure in landscapes or by magnetic fields in stellar atmospheres, reflecting a common idea of standout extensions across natural systems.