Ceres is the largest body in the asteroid belt, roughly 940 kilometres across, and since 2006 has been formally classed as both an asteroid and a dwarf planet, the only object to hold both designations. It is one of the four principal asteroids used in modern astrology, taking its name from the Roman goddess of grain and the harvest. When Ceres was found in 1801 astronomers briefly counted it among the planets, and it and the three that followed were each given individual glyphs in the style of the planetary symbols already in use, rather than the numbered-circle notation later adopted for the swelling ranks of asteroids discovered from the 1850s onward. That older convention of dedicated glyphs is what let Ceres, Pallas, Juno and Vesta carry distinctive symbols into twentieth-century astrological practice, long after most other asteroids had been reduced to a number in a circle.
William Herschel proposed the term asteroid, meaning starlike, for these new bodies because even through a telescope they showed as points of light rather than resolvable discs, unlike the planets they were first grouped with. Piazzi originally styled his find Ceres Ferdinandea, honouring both the Sicilian grain goddess and his patron King Ferdinand III, though astronomers elsewhere declined to adopt the royal half and only Ceres endured internationally. Modern measurements show Ceres alone accounts for roughly a third of the estimated total mass of the entire asteroid belt, and its 2006 promotion to dwarf planet came from the same International Astronomical Union meeting that famously demoted Pluto.