We stole glances through the driver's window, watching the thin curtain of light, now blue, now green, shimmering against the black night. An explanation of what causes the northern lights could not be given until an understanding of particle physics was developed. It's easy to imagine that peoples in ages past had a number of explanations. Hudson Bay Inuits believed the northern lights were torches of the Gods that lit the way for new spirits leaving the earth and entering heaven. An aurora, or a multi-colored glow in the night sky, is caused by events that take place far from our own planet.
Outer space is filled with charged particles, electric and magnetic fields, dust and cosmic rays.
In our neck of the galaxy, much of the space weather comes from the Sun. When these particles reach earth, they are pulled in by the earth's magnetic field. The earth can be thought of as a giant magnet, with lines of magnetic force curving out into space and converging on the north and south poles. Tomorrow, we'll describe how these particles lashing against the earth's atmosphere result in the colorful display we call the northern lights. It takes between 3 to 6 days for these particles to enter the earth's magnetic field.