A circular to subcircular region which is brighter than the surrounding area.

A strand of cool gas suspended over the photosphere by magnetic fields, which appears dark as seen against the disk of the Sun; a filament on the limb of the Sun seen in emission against the dark sky is called a prominence.

A bright meteor.

a narrow opening or crack of considerable length and depth.

Flow terrain.

A long, narrow, shallow depression.

A break or crack.

The rubbing of one surface or thing again another.