Simplify the following text for a Grade 11 native English-speaking person.
Original: It is the largest of the stony ( S-type ) asteroids , and somewhere between the 8th to 12th largest main-belt asteroid overall ( uncertainty in diameters causes uncertainty in its ranking ) .
Simplified: It is the biggest of the stony ( S-type ) asteroids , and somewhere between the 8th to 12th biggest Main Belt asteroid overall ( unsure diameters make its ranking unsure ) .