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 system Cosmic microwave background Supermassive black holes Heliocentrism Big bang nucleosynthesis Galaxy formation and evolution Kepler’s laws General relativity Gravitational lensing Galileo Special relativity Stars: types Newton’s laws of motion Black holes Stars: births of stars Gravitation String theory Stars: deaths of stars Spectrum Astroparticle physics Stars: life cycles Milky Way Cosmic rays The sun: fusion and sunspots Doppler shift and redshift Higgs boson Pulsars Shapley-Curtis debate Anthropic principle Cepheids and variable stars Olbers paradox Hubble sequence of galaxy types Gamma ray bursts Hubble’s law Dark matter Exoplanets Cosmic distance ladder Large scale structure Theories of creation Big bang Galaxy clusters and voids Earth-moon giant impact theory Cosmic inflation X-ray background Astrobiology Dark energy Radio galaxies Fermi paradox Matter and antimatter Quasars and active galactic nuclei