Enter a clue or pattern or both:
The Clue
They have umbras and penumbras (8 letter answer)
The Answer
SUNSPOTS
Tags
Notes
The answer SUNSPOTS is so rare that it appears less than once every 2500 puzzles.
Definition
SUNSPOT as a noun:
1. (sunspot, macula) = a cooler darker spot appearing periodically on the sun's photosphere; associated with a strong magnetic field