His geomagnetic surveys showed that auroral activity was almost uninterrupted. The idea that the ejected material consisted of both ions and electrons was first suggested by Norwegian scientist Kristian Birkeland. Eddington's proposition was never fully embraced, even though he had also made a similar suggestion at a Royal Institution address the previous year, in which he had postulated that the ejected material consisted of electrons, whereas in his study of Comet Morehouse he had supposed them to be ions. In 1910, British astrophysicist Arthur Eddington essentially suggested the existence of the solar wind, without naming it, in a footnote to an article on Comet Morehouse. Laboratory simulation of the magnetosphere's influence on the solar wind these auroral-like Birkeland currents were created in a terrella, a magnetised anode globe in an evacuated chamber. Irish academic George FitzGerald later suggested that matter was being regularly accelerated away from the Sun, reaching the Earth after several days. The following day, a powerful geomagnetic storm was observed, and Carrington suspected that there might be a connection the geomagnetic storm is now attributed to the arrival of the coronal mass ejection in near-Earth space and its subsequent interaction with the Earth's magnetosphere. This is a sudden, localised increase in brightness on the solar disc, which is now known to often occur in conjunction with an episodic ejection of material and magnetic flux from the Sun's atmosphere, known as a coronal mass ejection. In 1859, Carrington and Richard Hodgson independently made the first observations of what would later be called a solar flare. ![]() The existence of particles flowing outward from the Sun to the Earth was first suggested by British astronomer Richard C. Other related phenomena include the aurora (northern and southern lights), the plasma tails of comets that always point away from the Sun, and geomagnetic storms that can change the direction of magnetic field lines. The flow of the solar wind is no longer supersonic at the termination shock. Its particles can escape the Sun's gravity because of their high energy resulting from the high temperature of the corona, which in turn is a result of the coronal magnetic field.Īt a distance of more than a few solar radii from the Sun, the solar wind reaches speeds of 250–750 km/ s and is supersonic, meaning it moves faster than the speed of the fast magnetosonic wave. On average, the plasma density decreases with the square of the distance from the Sun while the velocity is nearly constant, see Figure 4.2. Near the Earth's orbit at 1 Astronomical Unit (AU) the plasma flows at speeds ranging from 250–750 km/s (155-404 mi/s) with a density ranging between 3-10 particles per cubic centimeter and temperature ranging from 10 4 to 10 6 degrees Kelvin. The solar wind varies in density, temperature and speed over time and over solar latitude and longitude. Superposed with the solar-wind plasma is the interplanetary magnetic field. There are also rarer traces of some other nuclei and isotopes such as P, Ti, Cr, 54Fe and 56Fe, and 58Ni, 60Ni, and 62Ni. The composition of the solar wind plasma also includes a mixture of materials found in the solar plasma: trace amounts of heavy ions and atomic nuclei such as C, N, O, Ne, Mg, Si, S, and Fe. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between 0.5 and 10 keV. ![]() The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona.
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