outer layers of Sun
Can only directly view the outer layers of the Sun
- like viewing into a murky pool of water -- what’s down there?
- structure and composition inferred using the laws of physics
- Visible layer (> 99% of light) called the “photosphere”
- i.e. region where the photons originate
- about 600 km thick f.8-1
- ~ 0.1% of the solar radius
- about as thick, relatively, as the skin on your body
- T ~ 6000 K
- hot enough to melt/vaporize all substances
- peak emission at 500 nm (green) -- Wien’s law
- above photosphere is “chromosphere”
- from Greek, “colored sphere”
- “pink” or “ruby red” region during total solar eclipse
- color from red Balmer ? line of H we saw in class