Iron planet
Mercury is the largest celestial body of this type in the Solar System (as the other terrestrial planets are silicate planets), but larger iron-rich exoplanets are called super-Mercuries.Iron is the sixth most abundant element in the universe by mass after hydrogen, helium, oxygen, carbon, and neon.Current planet formation models predict iron-rich planets will form in close-in orbits or orbiting massive stars where the protoplanetary disk presumably consists of iron-rich material.[2] Such planets would have no plate tectonics or strong magnetic field as they cool rapidly after formation.[3] In science fiction, such a planet has been called a "Cannonball".
mantleMercurySolar Systemterrestrial planetsexoplanetssixth most abundant element in the universe by masshydrogenheliumoxygencarbonrocky planetsimpactsprotoplanetary diskplate tectonicsmagnetic fieldgoldilocks zoneiron carbonylGJ 367bHD 23472LHS 3844 bDwarf planetExtrasolar planetTerrestrial planetWayback MachineWriter's Digest BooksBibcodePlanetDefinitionPlanetary scienceExoplanetExoplanet orbital and physical parametersMethods of detecting exoplanetsPlanetary systemPlanet-hosting starsTerrestrialCarbon planetCoreless planetDesert planetHycean planetIce planetLava planetOcean worldMega-EarthSub-EarthSuper-EarthGaseousEccentric JupiterMini-NeptuneHelium planetHot JupiterHot NeptuneGas giantIce giantSuper-JupiterSuper-NeptuneSuper-puffUltra-hot JupiterUltra-hot NeptuneBlanetBrown dwarfChthonian planetCircumbinary planetCircumtriple planetDisrupted planetDouble planetEcumenopolisEyeball planetGiant planetMesoplanetPlanemoPlanetesimalProtoplanetPulsar planetSub-brown dwarfSub-NeptuneToroidal planetUltra-cool dwarfUltra-short period planet (USP)Formation and evolutionAccretionAccretion diskAsteroid beltCircumplanetary diskCircumstellar discCircumstellar envelopeCosmic dustDebris diskDetached objectExozodiacal dustExtraterrestrial materialsExtraterrestrial sample curationGiant-impact hypothesisGravitational collapseHills cloudInternal structureInterplanetary dust cloudInterplanetary mediumInterplanetary spaceInterstellar cloudInterstellar dustInterstellar mediumKuiper beltList of interstellar and circumstellar moleculesMolecular cloudNebular hypothesisOort cloudOuter spacePlanetary migrationRing systemRubble pileSample-return missionScattered discStar formationSystemsExocometInterstellarExomoonTidally detachedRogue planetPulsarDetectionAstrometryMicrolensingPolarimetryRadial velocityTransit-timing variation