The Sun is always emitting a continuous stream of charged particles, mainly electrons and protons. Occasionally, eruptions called Coronal Mass Ejections (CMEs) occur, with higher density, energy and speed of the ejected particles. These events vary in strength. Strong ones bring dramatic Aurora displays on Earth, and very strong ones can disrupt communications. An unexpectedly strong blast from the Sun hit Mars Sept. 11, 2017. It sparked a global Aurora at Mars more than 25 times brighter than any previously seen by NASA MAVEN orbiter, which has been studying the Martian atmosphere’s interaction with the solar wind. It measured the collision intensity of Sun charged particles with Mars atmospheric gases before and after the CME event on the “night” side of Mars, which confirms the fact that Mars has a magnetic field but it is weaker than that on Earth. Arriving at high kinetic energy a charged particle can not stand still. As on Earth a charged particle begins to spiral along a magnetic field force line until it reaches one magnetic pole. It then slows down and U-turn back by spiraling along another magnetic field force line towards the other magnetic pole. As evidenced that their collision with Mars atmosphere shows on the dark side of the planet, proves that the oscillation of a charged particle between the two magnetic poles does not have to follow the same magnetic field force line that the particle spiraled around at the time it arrived at Mars.
A charged particle can carry its spiral path around a magnetic field force line that faces the Sun only to bounce back and pick up a spiral path around another magnetic field force line at random as with the case of Earth, which could be on the day side or the night side of the planet. Along the spiraling paths between the two magnetic poles, the collision of charged particles with one another produces energy the warms up the surface of the planet. The collision of charged particles and atmospheric gases would produce such Aurora lights that are observed on Mars. On Earth and due to its strong magnetic field, the entrapment of charged particles takes place at higher altitude and the only chance for charged particles to collide with Earth atmospheric gases is at the two magnetic poles, where magnetic field force lines converge into/ out of Earth and charged particle enter the lower atmospheric altitude; some to collide with air gases and some bounce back towards the other magnetic pole. On Mars, and due to its magnetic field weakness, the entrapment of charged particles takes place at lower altitude and accordingly the spiraling charged particles collide with Mars atmospheric gases at all times, along the day side and also night side magnetic field force lines.
This confirms the presence of a magnetic field on Mars and provides further credibility at the Martian climate model that I introduced earlier in 2009. An extract of which is available on Mars Warming page of this site.