The solar wind is made up of charged particles called plasma - mainly electrons and protons - that escape the Sun's powerful gravity and race across the Solar System.
The solar wind is powerful and is believed to have eroded or stripped away the atmospheres of other planets such as Mercury. Earth's relatively strong magnetic and gravitational fields have preserved its atmosphere from the constant onslaught. Observers near the poles sometimes see beautiful lights in the night sky known as auroras, the result of the solar wind interacting with Earth's magnetic field and atmosphere.
Photo: A coronal mass ejection, which is a type of violent solar plasma eruption that disrupts the solar wind (ESA/NASA)
Measurements made by the 1962 Mariner 2 spacecraft confirmed the presence of solar wind, a stream of particles from the Sun that stretches far beyond the outer planets. The Earth's magnetic field fights a constant battle against the solar wind's atmosphere eroding effects.
Sir Patrick Moore spoke to his guests, Professor John Zarnecki from the Open University and Professor Michele Dougherty from Imperial College, about Saturn's core, magnetic field and storms shortly after the Cassini-Huygens probe reached the ringed planet in 2004.
The solar wind is a stream of charged particles released from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time. These particles can escape the Sun's gravity because of their high kinetic energy and the high temperature of the corona.
The solar wind creates the heliosphere, an enormous bubble in the interstellar medium that surrounds the Solar System. Other related phenomena include geomagnetic storms that can knock out power grids on Earth, the aurora (northern and southern lights), and the plasma tails of comets that always point away from the Sun.
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