To begin with, subatomic particles such as electrons do not spin in the same way as the Earth spins on its axis. Spin is a quantum state that causes electrons and other particles to exhibit properties as if they were spinning, such as possessing a magnetic dipole moment (because electrons are charged), as well as a few other things. Symmetry with other subatomic particles demands that electrons have only two spin states, which are +1/2 and -1/2. This essential pairing of electron states is fundamental to chemistry; it is why, for example, the electron shells of atoms all have multiples of two electrons, but otherwise have room for the square of the number of valence shells from the nucleus (i.e. 2 = 2x1, 8 = 2x22 = 2x4, 18 = 2x32 = 2x9, etc.). However, there is no preferred direction to how electrons rotate as if they were genuinely rotating particles; spin is different from that.