A planetary nebula.

(astronomy) Of, or relating to planets, or the orbital motion of planets. / Of, or relating to the Earth; terrestrial. / Of, or relating to the whole Earth; global. / (of a gear train) epicyclic

plural of planetary

That branch of astronomy that deals with the planets of the solar system.

A system of gears that has a central gear wheel (sun gear) around which others (planet gears) rotate, often within an outer ring.

(astronomy) a ring of dust, moonlets and other matter that orbits a planet (such as Saturn) as a flat disc; gaps in the ring are due to the presence of shepherd moons

(astronomy) A nebulosity surrounding a dying red giant, consisting of material expelled by the star.

plural of planetary ring

plural of planetary aberration

(astronomy) A deviation of where a planet appears to be, due to the motion of the planet during the time that the light reaches the Earth.