Solar F corona

The exterior part of the solar corona, illuminated by solar light scattered or reflected by dust particles. The same phenomenon also produces the zodiacal light, much farther away from the Sun. The dust particles are at most several microns in size and make up a disk stretching over almost 1 solar radius (700,000 km) from the Sun's surface. Unlike electrons, which are responsible for the K corona, the dust particles move relatively slowly. Thus, the light scattered by them has the same spectrum as the photosphere and shows the Fraunhofer lines. The F corona is the most luminous part of the corona at 1.5 solar radii from the Sun's surface.