HYPOTHETICAL ASTRONOMICAL OBJECT ASTRONOMICAL OBJECT STAR PLANET MOON BELIEVED SPECULATED EXIST WHOSE EXISTENCE SCIENTIFICALLY PROVEN HYPOTHESIZED RECORDED HISTORY THE CENTURY THE PHILOSOPHER PHILOLAUS DEFINED THE CENTRAL FIRE CELESTIAL BODIES INSIDE OUTSIDE THE SOLAR SYSTEM SPECULATION ASTRONOMICAL OBJECTS SEE LIST SOLAR SYSTEM BROWN DWARF BROWN DWARFS EXTRASOLAR MOON PLANETS MOONS ACCEPTED SCIENCE PLANETARY OBJECTS PROPOSED IN UFOLOGY PSEUDOSCIENCE HYPOTHETICAL PLANETS IN FICTION FICTIONAL PLANETS OF THE SOLAR HYPOTHETICAL TYPES OF EXTRASOLAR PLANET CARBON PLANET TERRESTRIAL PLANET RATHER SILICON CHTHONIAN PLANET HOT JUPITER OUTER LAYERS STRIPPED PARENT CORELESS PLANET CORE GOLDILOCKS PLANET LIES CIRCUMSTELLAR HABITABLE ZONE THE RIGHT DISTANCE SUPPORT HELIUM PLANET GAS GIANT PLANET WHITE DWARF STAR HELIUM HYDROGEN IRON PLANET MERCURY IRON LITTLE MANTLE OCEAN PLANET SURFACE DEEP OCEANS ROGUE PLANET TIED WANDERING THE GALAXY TROJAN PLANET ORBITS