From what I've read, this is called 'concentric cracking.' It appears to be caused by either too much water following too little
water; very fast growth with high temperature and moisture; or a large difference between day and night temperatures.
Basically, either heat or rapid growth is causing the inside of the fruit to expand faster than the outside can, resulting in the
skin being split.
The rest of the fruit is still edible, once you cut away the affected parts.