Yesterday, the Earth moved into a high speed stream of the solar wind. What is the solar wind? Answer: a wave of charged particles emitted from the Sun at high speed into space. So, what does this all mean for us here on Earth?
The aurora are caused when the energized particles from the Sun come into contact with Earth's upper atmosphere. When the charged energy hits Earth, the particles react and the atoms/molecules in Earth's upper atmosphere give off the photons we see as the Northern Lights. Why are the lights different colors? Each individual atom gives off a different glow when excited by the incoming solar wind.
For us living in the Northern hemisphere, auroras are common in high latitudes such as Alaska, Canada, the Scandinavian countries, and other such high-latitude places. For those at mid latitudes, such as the Northern continental United States, auroras don't find their way into these skies very often, but when they do, they are often dazzling.
However, it never hurts to look.
Right now, the Sun is at maximum, the peak in activity in its 11-year cycle. Because blasts of energy from the Sun are at their peak power, the chances of aurora working their way down to the continental United States is at its highest. In May, 2005, I saw a stunning display of auroras that ranged from blue-violet overhead to green curtains near the horizon from the Cleveland, Ohio area (41 degrees North).
Right now, according to spaceweather.com, one should keep an eye on the sky tonight as the Earth is still within the solar wind, which could mean more aurora tonight.
As always, would-be sky watchers in the Cleveland area should be sure to keep an eye on the Cleveland weather forecast and, for hour-by-hour cloud predictions, the Cleveland Clear Sky Clock. Live somewhere else? Find a clock and see if it will be clear near you.
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