Original: One of Phaethon's most remarkable distinctions is that it approaches the Sun closer than any other numbered asteroid; its perihelion is only 0.140 AU - less than half Mercury's perihelion distance.
Simplified: Phaethon approaches the Sun closer than any other numbered asteroid. Its perihelion (closest approach to the Sun) is only 0.140 AU - less than half Mercury's perihelion distance.