planetary nebula
— Navneord
– Engelsk
~ a nebula that was once thought to be a star with its planets but is now thought to be a very hot star surrounded by an expanding envelope of ionized gases that emit a fluorescent glow because of intense radiation from the star
planetesimal
— Navneord
– Engelsk
~ one of many small solid celestial bodies thought to have existed at an early stage in the development of the solar system
planetesimal hypothesis
— Navneord
– Engelsk
~ (cosmology) the theory that the solar system was formed by the gravitational accumulation of planetesimals
planethjul
— Navneord
– Dansk
~ mindre tandhjul der griber ind i og bevæger sig ru ...
planetoid
— Navneord
– Engelsk
~ any of numerous small celestial bodies that move around the sun