 |
||||
    |
    |
|||
|
Interplanetary environment >> Solar radiations The Sun continuously emits two kinds of radiation: electromagnetic and corpuscular.
Electromagnetic solar radiation Electromagnetic solar radiation is a phenomenon by which energy escapes from the Sun at the speed of light in the form of a wave. There are several types of radiation that can be expressed in terms of energy, wavelength or frequency (number of waves per second). The best known type of the spectrum is visible sunlight.
In a rainbow, the solar rays are arranged according to their wavelength (see above illustration). From purple to red, the wave gets longer. The infrared, with a wavelength larger than the one of red, is not visible, but we feel its warmth. The ultraviolet (UV) has a wavelength smaller than the one of purple. This part of the solar radiation, which is not visible either, can be harmful for humans. More...
Solar wind Solar wind is plasma: a flow of charged particles (ions and electrons) which is continuously escaping from the Sun into the interplanetary medium. More...
Cosmic radiation Cosmic radiation is made up of a flow of very high energy particles mostly hydrogen nuclei (protons) and helium nuclei (alpha particles). These radiations are caused by solar flares and coronal mass ejections but also by supernovae (explosion of stars) in the core of our galaxy and by other objects outside our galaxy. The energy of these particles vary from a few hundreds of MeV (mega-electron-volt) to dozens of GeV (giga-electron-volt). Cosmic radiation is partly blocked by Earth’s atmosphere. These radiations are a real danger for astronauts and satellites in orbit around the Earth. When astronauts are performing work outside the protection of their spacecraft “extra-vehicular activity” they can be exposed to very high amounts of radiation.
|
||||
 |
 |
|||
 |
||||
