Simplify the following text for a Grade 9 native English-speaking person.
Original: Ixion is a plutino ( an object that has a 2:3 orbital resonance with Neptune ) and a dwarf planet candidate ; its diameter of 650 km estimated by Spitzer makes it about the fifth largest plutino .
Simplified: Ixion is a plutino ( an object that has a 2:3 orbital resonance with Neptune ) and could be a dwarf planet .