The Corona through the solar cycle
Not surprisingly, the changes in the surface magnetic field distribution through the solar cycle, as evidenced by the evolving numbers and spatial distributions of sunspots, prominences and filaments, are also reflected in the corona.
The top row of images are X-ray images from the Yohkoh
satellite, spaced approximately 10 months apart during the descending part
of cycle 22. The overall decrease in X-ray luminosity for the solar disk
as a whole is in many ways as spectacular as the decrease in the number
of active regions seen at a given time on the disk. The bottom row shows
a few eclipse photographs spanning the time period 1966---1988, together
with a coronal image constructed from Solar Maximum Mission data for 1985,
essentially at solar minimum. Note how the corona is reduced to a belt
of streamers symmetrically straddling the solar equator.
Solar Corona over 6 yrs