準じゅん惑わく星せい

noun

dwarf planet

Astronomical term for a celestial body that orbits the sun and is massive enough to be rounded by its own gravity, but has not cleared its neighboring region of planetesimals. Used in modern astronomy since the 2006 IAU definition.

• 冥めい王おう星せいは2006年ねんに準じゅん惑わく星せいに分ぶん類るいされた。

  Pluto was classified as a dwarf planet in 2006.

• 太たい陽よう系けいには現げん在ざい5つの準じゅん惑わく星せいが確かく認にんされている。

  There are currently five recognized dwarf planets in the solar system.