Solar Eclipse
From Blaseball Wiki
A Solar Eclipse is an astrological phenomenon in which the Sun is obscured from view by the intercession of the Moon or other object. It is one of the potential weather variants under which a blaseball game may occur. Its effects on the game of blaseball are currently unknown.
When The Book was opened and The Discipline Era began, a solar eclipse began, lasting for the entirety of Season Two and significantly reducing visibility during games.