The Sun's outer gases extend far beyond the photosphere (Figure 6). Because they are transparent to most visible radiation and emit only a small amount of light, these outer layers are difficult to observe. The region of the Sun's atmosphere that lies immediately above the photosphere is called the chromosphere.
You can't hear sound on the moon because of space. Space is a vacuum so you can't hear anything unless there is a medium for it to travel through (like air)
