Hydrogen is the most abundant element found on the sun. The sun’s “surface” and the layer just above it — the photosphere and chromosphere, respectively — are regions where atomic hydrogen exists profusely in upper-state form, and it’s these absorption layers that hydrogen alpha imaging reveals in detail.

The “furry” texture of the sun’s surface is caused by structures called “spicules” — vertical tongues of superheated plasma that flare up from the photosphere. When observed inside the sun’s disk, the darker horizontal structure of spicules are known as “fibrils.” Plasma accelerated in spicules can travel vertically up to 55,000 mph and reach 3,000 miles (4,830 kilometers) in altitude before fizzling out — fibrils, on the other hand, appear somewhat less dynamic. There’s an estimated 100,000 spicules distributed across the face of the sun at any one time.”

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