What is radio aurora?
If there are enough charged particles (electrons) spiralling down the earth’s magnetic field lines, the ionization may be sufficient to reflect VHF and lower UHF radio waves (generally in the 25 to 500 MHz freqency range). This usually occurs in conjunction with visual aurora, but the mechanism is a bit different and it is possible to have one (visual or radio) without the other. This is how auroral radars work – they send a VHF radio signal toward the auroral oval and record the strength of the signal reflected back from the aurora.
