Mariner 10 radiation. The plasma experiment's goal was to study the ionized gases (plasma) of the solar wind, the temperature and density of its electrons, and how the planets affected the velocity of the plasma stream. The experiment contained two components, facing in opposite directions. The Scanning Electrostatic Analyzer was aimed toward the Sun, and could detect positive ions and electrons, which were separated by a set of three concentric hemispherical plates. The Scanning Electron Spectrometer was aimed away from the Sun, and detected only electrons, using just one hemispherical plate. The instruments could be rotated about 60 degrees to either side.
Universe one up quark; and the electron is a kind of lepton. An atom consists of an atomic nucleus, made up of protons and neutrons, and electrons that orbit the nucleus. Because most of the mass of an atom is concentrated in its nucleus, which is made up of baryons, astronomers often use the term "baryonic matter" to describe ordinary matter, although a small fraction of this "baryonic matter" is electrons. Soon after the Big Bang, primordial protons and neutrons formed from the quark–gluon plasma of the early Universe as it cooled below two trillion degrees. A few minutes later, in