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.
Rebel Alliance
During the events of "Rogue One" and "A New Hope", the Alliance learns of the construction of the "Death Star", an enormous battle station intended to secure the Empire's power. With the help of the "Rogue One" squad led by Jyn Erso and Cassian Andor, the Rebels successfully steal the schematics of the station. This win was the Alliance's first major battle against the Empire on Scarif; but at a 75% casualty rate and with all remaining imperial and rebel forces planetside decimated. After successfully downloading the Death Star plans, Alderaanian soldiers aboard a Mon Calamari flagship barely manage to escape Imperial forces with the stolen data plans. Right after the battle, the "Tantive IV", an Alderaanian corvette carrying Princess Leia Organa is captured by the Imperial fleet while attempting to deliver the Death Star Plans to Bail Organa on Alderaan. All members of the Alderaanian Consular Security onboard are either killed or taken prisoner and Princess Leia Organa is held hostage for a time by Darth Vader. In order to punish both her and her home planet's central involvement in the Rebel Alliance, Leia is forced to witness Alderaan's destruction by the Death Star. The Princess is subsequently rescued by Luke Skywalker, Han Solo, Chewbacca, and Obi-Wan Kenobi, who then deliver the station schematics to the Alliance. This leads directly to the Alliance's victory in the Battle of Yavin and the loyalty of Luke Skywalker; the Rebellion's only remaining member with training in the Force.