Physics and Star Wars
To estimate the effects of the second Death Star, Minton looks into its mass. According to estimated data from some students of Lehigh University, the steel mass needed for building one would be around 770 kilograms times the mass cubed in weight. This would give the Death Star of about ten to the power of nineteen kilograms in mass. Using this data, Minton produces equations that lead him to conclude the fragments would hit the moons surface so hard causing craters almost four times the size of the Chicxulub crater in Mexico. This impact would cause a planetary firestorm and vaporize all lifeforms on the moon.
Death Star
In the animated series "Star Wars Rebels", the two-part episode "Ghost of Geonosis" hinted that the Geonosians were nearly wiped out to extinction out of the Empire's need for secrecy. Saw Gerrera, having been sent to Geonosis to investigate, deduced the Empire possesses a superweapon and resolved to discover the Death Star as depicted in the final season two-parter "In the Name of the Rebellion." Though it was a dead end, finding only scientists being abducted by the Empire, Saw learned the weapon is powered by kyber crystals taken from the Jedha system.