In Star Trek Into Darkness (STID), we see the Klingon homeworld of Kronos, and its moon. The moon is essentially destroyed; it orbits Kronos in large pieces of its former self.
A recent answer reminded me that in the film Star Trek VI: The Undiscovered Country, Qo'noS' moon Praxis is destroyed. Admittedly, these are two separate timelines, but the destruction of the moon in ST6 takes place long after the timeframe depicted in STID. This suggests a different catastrophe caused the destruction of Praxis in STID.
What caused the destruction of Praxis in Star Trek Into Darkness?