The brighter yellow and red areas indicate active areas of the sun likely with sun spots and from which flares are likely to occur.
This is a neat pic
STEREO Ahead used to be out in space at about a 45 degree angle from the Earth's position in orbit and showed us what was coming 'around the bend'.
Contact with STEREO Behind was lost in 2014 and it remains dead.
STEREO ahead has moved closer to the earth and its usefullness to see the far side is over. In August of 2023 it became in line with the earth and seeing the same view we do. It will continue move and become able to view what has rotated past us, becoming in essence, STEREO Behind.
