Complex sentence: The object was undetected before its atmospheric entry, in part because its radiant was close to the Sun. Its explosion created panic among local residents and about 1,500 people were injured seriously enough to seek medical treatment.
Split into simpler sentences: The object was undetected before its atmospheric entry, in part because its radiant was close to the Sun, and its explosion created panic among local residents. About 1,500 people were injured seriously enough to seek medical treatment.