In this, the latest volume in the best selling 50 Ideas series, author Joanne Baker unravels the complexities of the universe for a general readership.From Heliocentrism to dark matter, and from Kepler's laws of planetary motion and orbits to Olber's paradox and the Shapley-Curtis debate, she explains ideas at the cutting-edge of scientific enquiry, making them comprehensible and accessible to the layperson.Planets and solar systemCosmic microwave backgroundSupermassive black holesHeliocentrismBig bang nucleosynthesisGalaxy formation and evolutionKepler's lawsGeneral relativityGravitational lensingGalileoSpecial relativityStars: typesNewton's laws of motionBlack holesStars: births of starsGravitationString theoryStars: deaths of starsSpectrumAstroparticle physicsStars: life cyclesMilky WayCosmic raysThe sun: fusion and sunspotsDoppler shift and redshiftHiggs boson PulsarsShapley-Curtis debateAnthropic principleCepheids and variable starsOlbers paradoxHubblesequence of galaxy typesGamma ray burstsHubble's lawDark matterExoplanetsCosmic distance ladderLarge scale structureTheories of creationBig bangGalaxy clusters and voidsEarth-moon giant impact theoryCosmic inflationX-ray backgroundAstrobiologyDark energyRadio galaxiesFermi paradoxMatter and antimatterQuasars and active galactic nuclei