Simplify the following text for a Grade 8 native English-speaking person.
Original: During the comet 's run into the closer part of the solar system for the first time in 500,000 years , the nucleus of Comet West was seen to split into four pieces as it passed within 30 million km .
Simplified: As the comet passed within 30 million km of the Sun , the nucleus was observed to split into four fragments .