How Stars Work

What happens in a star’s photosphere?

The photosphere is the layer of a star’s atmosphere that we see when viewing the Sun in visible light. It is sometimes referred to as the “surface” of a star. It is a few hundred miles thick, and it is made up of planet-sized cells of hot gas called granules. These gas cells are in constant motion, continuously changing size and shape as they carry heat and light through from the Sun’s interior to its exterior. Sunspots, regions of intense magnetic activity, also occasionally appear in the photosphere and last from hours to weeks.


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