The solar wind is a continuous stream of very energetic particles coming, as its name indicates, from our star. On Earth, the solar wind is responsible for forming the northern lights, but it can also be bad for the satellites that orbit the Earth.
The solar wind is made of plasma, a state of the matter in which the atoms have been ionised, that to say, they have lost one or more electrons. So, the solar wind is composed of electrons that travel freely through space, and the nuclei (formed by protons and neutrons) that the electrons have left behind.
Moreover, as the Sun is made of hydrogen and helium in 98%, the atom nuclei present in the solar wind are mainly the ones of these two elements.
The emission of the solar wind
Just like the Earth, the Sun is composed of diverse layers. The most superficial layer (the one farther away from the nucleus) is named the corona, and it is at a temperature of about 1.1 million degrees Celsius (2 million degrees Fahrenheit).
The corona isn’t the surface of the Sun itself but is a sort of “cloud” (from here comes the name of the corona) that is situated above the actual surface of the Sun, and it extends to about 10 million kilometres from it. At this distance, there is a point of transition from which the corona is converted into the solar wind. At this point, the Sun’s magnetic field isn’t strong enough to retain the subatomic particles that comprise the corona.
Once far away from the Sun’s attraction, the plasma that forms the solar wind travels, at a speed that varies between 400 and 900 kilometres per second, to all the directions of the solar system.