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Sunspot
- Large, dark features seen on the surface of the Sun
- Caused by increased magnetic activity
- The magnetic field lines are twisting due to differential rotation
- The twisting creates knots which show up as sunspots
- Cooler than the surrounding areas of the sun
- ~3800 K vs. ~5800 K
- Still hotter than the surface of many stars
- Consist of two spots
- Umbra
- Inner dark core
- Penumbra
- Surrounding less dark region
- Umbra
- Can become bigger than Earth
Sunspot Cycle
- Number of sunspots varies systematically
- Cycles every decade or so
- Sunspot maxima occur at an average interval of 11 year
- More than 100 sunspots can be seen at once