Friday, December 7, 2012

APOD 6.7

Winter is here, and in places where it actually snows--like this area near Madrid, Spain--the ice crystals morph the atmosphere into a giant lens, arcs and halos forming around the sun or the moon (whichever is visible at the time). This sky displays the moon with not one, not two, not even three, but four halos radiating from the bright face. The lunar beams refact through hexagonal ice crystals which creates a 22 degree halo around her, while the elongated circumscribed halo is formed from column ice crystals. Here's where it gets interesting: the third rainbow ring forms from yet another refraction at a 46 degree angle thanks to distant ice crystals, and the fourth and final ring at 46 degrees makes this a quadruple halo; twice as cool as a double rainbow. In the distant celestial scape, Betelgeuse, Sirius, and Orion's Belt are visible, all over the landscape of Puerto de Navacerrada in the mountain range of Sierra de Guadarrama.