September's Aurora
September's equinox arrives today at 0905 UT. As the Sun crosses the celestial equator
heading south, spring begins in the southern hemisphere and autumn in the north. And
though the seasonal connection is still puzzling, both spring and autumn bring an increase
in geomagnetic storms. So as northern nights grow longer, the equinox also heralds the
arrival of a good season for viewing aurora. Recorded earlier this month, these curtains
of September's shimmering green light sprawl across a gorgeous night skyscape. In the
foreground lies Hidden Lake Territorial Park near Yellowknife, Northwest Territories,
Canada. Calm water reflects the aurora, with bright star trails peering through the
mesmerizing sky glow. Of course, shining at altitudes of 100 kilometers or so, planet
Earth's auroras are visible from space.