I would like to have a planet in which somehow it becomes necessary to harvest aurora for energy (and maybe matter if that's feasible).
The civilization of this planet is moderately advanced -- enough to have colonized other planets in its solar system, but not enough to have travel between stars.
Which of the following would improve the plausibility of harvesting aurora:
- A planet smaller or bigger than the earth
- A planet with a weaker or stronger magnetic field
- A planet closer or further away than the earth
- A sun smaller or bigger than our sun
- A higher rate of solar activity
- A planet with a smaller or bigger atmosphere (or no atmosphere)