A Rondelet; The Northern Lights
resulting from a large, strong solar flare.
beautiful on the long, cold winter nights,
dancing through Ursa Major, the Great Bear.
Astonishing all who will stop and stare
The Rondelet is a French form with seven lines, three of which are repeated as refrains in lines 1, 3 and 7. The other lines are twice as long with a rhyme scheme of AbAabbA.
Examples can be found in the following link: http://lotrscrapbook.bookloaf.net/poetry/forms/rondelet.html