• Large, dark features seen on the surface of the Sun
  • Caused by increased magnetic activity
  • 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
  • Can become bigger than Earth

Sunspot Structure

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

Sun Astronomy