Complex sentence: The second Death Star was a sphere of machinery somewhere between 180 and 900 kilometers in diameter (depending on the sources one holds to be authoritative) and it was located very close to Endor's forest moon when it exploded.
Split into simpler sentences: The second Death Star was a sphere of machinery somewhere between 180 and 900 kilometers in diameter (depending on the sources one holds to be authoritative). It was very close to Endor's forest moon when it exploded.