GCSE›AQA GCSE Physics›Mind mapsOur Solar SystemAQA GCSE Physics: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsWhat's in it?One star: the SunEight planets orbit the SunDwarf planets have not cleared their orbital pathMoons are natural satellites orbiting planetsPart of the Milky Way, which has billions of starsFormation of the SunFormed from a nebula of dust and gasGravity pulled the cloud togetherContracting cloud heated up until fusion beganFusion releases huge amounts of energyStable starGravity pulls inwards, fusion pushes outwardsBalance is an equilibriumKeeps the star a stable size for most of its lifeSolar Systemthe Sun and its orbitersSun8MoonOrbitsGravity keeps planets, moons and satellites in orbitWithout gravity, objects go off in a straight lineGravity provides the centripetal forceArtificial satellites are human-made, moons are naturalCircular orbits (HT)Gravity acts towards the centre at all timesSpeed stays constantDirection changes, so velocity is always changingSpeed changes mean the orbit radius must changeExam tipsNever say satellites have no force acting on themConstant speed still needs a resultant forceDistinguish natural from artificial satellites