my very educated mother just served us nine pumpkins

From the initial letters of the names of the eight planets, plus Pluto, formerly considered a planet.

my very educated mother just served us nine pumpkins

1. (astronomy, slightly dated, mnemonic) Used to remember the order and names of the (then) nine planets of the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto.

• Pluto was relegated to status of dwarf planet by the IAU in 2006.