Before revision: A near-Earth supernova is an explosion resulting from the death of a star that occurs close enough to the Earth (roughly less than 10 to 300 parsecs ( 30 to 1000 light-years ) away) to have noticeable effects on Earth's biosphere.
After revision: A near-Earth supernova is an explosion resulting from the death of a star that occurs close enough to the Earth roughly less than 10 to 300 parsecs ( 30 to 1000 light-years away) to have noticeable effects on Earth's biosphere.