Aurora, Amazing Northern Lights

The energization of such electrons comes from magnetotail processes. The leakage of negative electrons does not leave the tail positively charged, because each leaked electron lost to the atmosphere is quickly replaced by a low energy electron drawn upwards from the ionosphere. Such replacement of "hot" electrons by "cold" ones is in complete accord with the 2nd law of thermodynamics.
Other types of auroras have been observed from space, e.g. "poleward arcs" stretching sunward across the polar cap, the related "theta aurora", and "dayside arcs" near noon. These are relatively infrequent and poorly understood. There are other interesting effects such as flickering aurora, "black aurora" and subvisual red arcs. In addition to all these, a weak glow (often deep red) has been observed around the two polar cusps, the "funnels" of field lines separating the ones that close on the day side of Earth from lines swept into the tail. The cusps allow a small amount of solar wind to reach the top of the atmosphere, producing an auroral glow.