Simplify the following text for a Grade 4 native English-speaking person.
Original: When Damocles was discovered , in 1991 by Robert H. McNaught , it was found to be on an orbit completely different from all others known .
Simplified: When Damocles was found , in 1991 by Robert H. McNaught , it was found to be on an orbit that was very different from all others known .