There’s one less planet in the solar system today now that Pluto has officially been demoted.

Once known as the smallest planet furthest from our sun, Pluto, discovered in 1930, was reclassified Thursday as a “dwarf planet” by the International Astronomical Union General Assembly.

The assembly, meeting in Prague, ruled that a planet must meet three specific criteria: have enough mass and gravity to gather itself into a ball; it must orbit the sun; and must reign supreme in its own orbit having “cleared the neighborhood” of other competing bodies.

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune meet those requirements. Pluto, however, shares the outer solar system with thousands of other Pluto-like objects.