text: 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 .