Earth, the third planet from the Sun, as far as we know until now, is the only planet where there is life: that, thanks to the water of its oceans and the oxygen of its atmosphere.
Compared to Mercury, that is very hot, and to Neptune, very cold, Earth is at a suitable distance from the Sun.
Although quite small in size, it is very heavy because of its iron core.
The motion of the liquid iron gives rise to an extensive magnetic field, which shields Earth from the harmful particles coming from the Sun.
The atmosphere instead, stops the most dangerous solar radiations.
