Mottles are features that form the chromospheric network on the Sun, visible in H-alpha and calcium K-line spectrograms. They cover the whole Sun, quiet and active regions alike. Coarse mottles are bright, up to 20,000 kilometers across, and often elongated; they merge to form plages. Fine mottles are narrow (700 kilometers wide and up to 7,000 kilometers long), dark or bright, and are probably spicules seen against the disk. Fine mottles form clusters with their bases rooted in the coarse mottles. All coincide with regions of strong magnetic field on the photosphere.
Related category SOLAR TOPICS
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