Mars losing its atmosphere. Artist's impression of the martian atmosphere eroded by the solar wind. The solar wind is a stream of particles, mainly protons and electrons, flowing from the sun (background) at a speed of about one million miles per hour. The magnetic field carried by the solar wind as it flows past Mars (foreground) can generate an electric field which accelerates ions (coloured particles) in Mars' upper atmosphere and shoots them into space. The loss of atmospheric gases increases during solar storms, and over time has contributed to the change in the Martian climate from warm and moist to cold and arid.