
One may see that, planets with no atmosphere like Mars; have not sufficient magnetic field, though whose core is solid nickel iron. And, here is the root of this innovative theoretical paper. We learn that the cause and origin of Earth's magnetic field is its iron core. But, to magnetize an iron core; a magnetic field is to be applied to hot iron in one direction continuously during its smooth cooling process. There is Ionosphere around Earth atop its atmosphere. The ionosphere of Earth contains electrical charges. The ionosphere rotates around Earth in opposite direction of its rotation about its own axis. Then as per electromagnetic laws; the ionosphere must be generating and providing magnetic field passing through Earth's iron core constantly. Then working on this theme electromagnetically, it is found that, the magnetic field of Earth is due to the Earth's Ionosphere. The iron core provides it low reluctance path. The Earth's magnetic field is very complex at its poles, always unstable. This is because of complex nature of ionosphere, containing +ve ions in ionosphere nearer to Earth's surface and -ve charges beyond it. Thus the basic theoretical computational study in respect of the ionosphere and iron core of Earth, and Mars as support to it; is performed in this innovative original paper.