Moondogs are even more rare then sundogs, but both of them can occur all year long. Auroras appear to be like luminous curtains of multicolored light draping over the night sky. Auroras are formed when charged solar particles collide with gas molecules in the earth's atmosphere and produce bursts of visible light. This phenomenon is known as the aurora borealis in the Northern Hemisphere and the aurora australis in the Southern Hemisphere. However, the borealis has been seen as far south as Mexico City and the australis has been seen as far north as Brisbane, Australia.
Auroras are especially unique because they can actually be hazardous.
They disrupt radio communications, because they create static. Auroras generally appear in the high latitudes, but can appear in the lower latitudes like the examples given above. Haloes are white or faintly colored rings encircling the sun or moon . When a haloe has visible colors, red appears closest to the center and blue on the outside. Note this is the opposite of coronas, which were previously discussed.