Longtime aurora watchers will know the Earth's two equinoxes — late March and late September — mark the most colorful times of the year. Aurora hunters claim that, to look to the night sky in search of these beautiful displays, the dates around the equinoxes are the best.
Science supports their wisdom. The data show that auroras peak around the two equinoxes and, on the other hand, auroras decline around June and December, the two solstices. The sun, of course, is not tied to Earth's rotation. So scientists have long tried to understand what ties geomagnetic storms — and the resulting auroras — to the calendar.
