The Photosphere

Our Sun in visible light showing sunspotsOur Sun's apparent surface is called the photosphere. Because the Sun is completely made of gas there is no hard surface like there is on earth. Nonetheless, when we look at the Sun there is a depth past which the gas begins to get so dense that we cannot see through it.

The photosphere is the disk you see in the sky when you look at the Sun through a filtered telescope or as a projection on a piece of paper.

WARNING You should never look at the Sun directly, it can cause blindness.

When you look at the Sun with a filtered telescope you can see evidence in the photosphere of the convective bubbles in the convection zone below. The continuous rising and falling of hot and cool bubbles produces a pattern on the surface of the Sun that is referred to as granulation. Below is a blown-up photograph of granulation around a sunspot on the photosphere.

Sunspot with nearby

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Image Credits:
Sun in Visible Light: Lockheed Martin Palo Alto Research Lab
Sunspot and Granulation: P. Brandt, G. Simon, G. Scharmer, D. Shine (Kiepenheuer, Uppsala, Lockheed)