This magnetic field is produced by the spinning of hot molten iron at the Earth's core and extends several tens of thousands of kilometers into space. It is called the magnetosphere. The magnetosphere shields the surface of the Earth from the charged particles of the solar wind emitted by the Sun. These solar winds would otherwise be fatal to life on Earth.

Planets with a weak or non-existent magnetic field are subject to atmospheric stripping by the solar wind. Mars does not presently have a global magnetic field. The presence of the solar wind, for billions of years, has contributed to the loss of water and the erosion of Mars' atmosphere.

The center of the Earth is a large, very strong bipolar magnet. However, by the time this magnetic field reaches the Earth's surface it ranges only about .3 to .6 gauss.

Carl Friedrich Gauss first measured the strength of the Earth's magnetic field in 1835. Scientists have measured and tracked the strength of this field since then. They have showed a decrease of about 10% over the past 150 years.

The Earth's surface magnetism is the strongest at two points – one near the geographic North Pole and the other near the geographic South Pole. These two areas have the densest concentration of magnetic flux lines. Magnetic fields are the strongest where the magnetic flux lines are the closest together. This occurs at the north and south poles of all magnets.

The Earth also has an electric field caused by the action of high-energy ultraviolet light coming from the Sun, which creates charged particles (ions) in the ionic atmosphere (ionosphere). The ionosphere is the uppermost part of the Earth's atmosphere.

Due to the perpendicular angle of the magnetic field near the poles, some charged particles make it into our atmosphere. This results in the polar auroras, sometimes called the northern lights or southern lights. This natural light display usually occurs in the ionosphere and can be seen in the sky near the Polar Regions.

The Earth's natural electromagnetic field is one of the fundamental forces of nature and is essential for life, unlike the man-made extremely low frequency electromagnetic fields (EMFs) which emit electromagnetic radiation and have been linked to cancer and numerous other conditions.