in about 1928. Hannes Alfvén won the Nobel Prize for his development of magnetohydrodynamics (MHD) the science that models plasma as fluids. This book lays down the ground work, but also shows that MHD may be inadequate for low-density plasmas such as space plasmas. Astronomy and astrophysics Favoured the heliocentric model (first advanced by Aristarchus) over the Ptolemaic model of the solar system; sometimes credited with starting the Scientific Revolution in the Western world. Provided strong arguments for heliocentrism and contributed valuable insight into the movement of the planets, including the first mention of their elliptical path and the change of their movement to the movement of free floating bodies as opposed to objects on rotating spheres (two of Kepler's laws). One of the most important works of the Scientific Revolution. Developed the third of Kepler's laws. Astrophysics Astrophysics employs physical principles "to ascertain the nature of the heavenly bodies, rather than their positions or motions in space." A landmark article of stellar physics, analysing several key processes that might be responsible for the synthesis of chemical elements in nature and their relative abundances; it is credited with originating what is now the theory of stellar nucleosynthesis. Introduction of the Faber–Jackson law relating galaxy luminosity and velocity dispersion. Introduction of the Tully–Fisher relation between galaxy luminosity and rotation-curve amplitude. Introduction of the M–sigma relation between black hole mass and galaxy velocity dispersion. Cosmology Penzias, A.A.; Wilson, R.W. (1965) "A Measurement of Excess Antenna Temperature at 4080 Mc/s." Discovery of cosmic microwave background radiation, early evidence for the big bang model. The authors were awarded the Nobel Prize in Physics for their joint works. Introduced the conditions necessary for baryogenesis, by making use of recent results (discovery of CP violation, etc). Republished in . Reference textbook on cosmology, discussing both observational and theoretical issues. Reported results from the COBE satellite, which was developed by NASA's Goddard Space Flight Center to measure the diffuse infrared and microwave radiation from the early universe to the limits set by our astrophysical environment. Measurements by a Far Infrared Absolute Spectrophotometer (FIRAS) confirmed that the cosmic microwave background (CMB) spectrum is that of a nearly perfect black body with a temperature of 2.725 ± 0.002 K. This observation matches the predictions of the hot Big Bang theory extraordinarily well, and indicates that nearly all of the radiant energy of the Universe was released within the first