The northern lights should return for a second show tonight starting at nightfall and continuing through about 10 p.m. Central time. Last night’s display, lovely as it was, ended so quickly it took many aurora watchers by surprise. When seeking signs of the lights, keep an eye on the north. Almost every show begins with a low, greenish arc often hidden by trees but revealed when you find an observing spot with an open view to the north.
The arc can be static, fade or brighten. If it brightens and especially if a second arc appears, stick around. Chances are the aurora will build in intensity and break into a silent parade of pillars or feathers of light. While you’re out looking for green this evening, you’ll be in the company of six astronauts. Yes, the space station’s back and will be making convenient evening passes through mid-April.
I caught an early one in the series last night, when the ISS floated up from the southwestern horizon and slid under Sirius, the sky’s brightest star. Looking as bright as Jupiter, the station steadily rose up into the southern sky moving east. Two minutes later it began to fade and then quickly disappeared from view as it was eclipsed by Earth’s shadow.
Find out when the football field-sized orbiting laboratory flies 250 miles over your head by logging into Heavens Above (click the ISS link to get a table of passes; clicking the time will pop open a map of the sky with the station’s path) or downloading the free ISS Spotter app for iPhone / ISS Detector for Android.
Taking advantage of Earth’s west to east rotation, the space station will always first appear in the western sky in the sunset direction and travel to the east. A typical pass lasts about 5 minutes though some are shortened to 1 or 2 minutes because the ISS enters Earth’s shadow. During early evening passes, the shadow is still low, so we get to see the satellite cross the entire sky. During later passes, the shadow has risen higher to cover more of the sky at the space station’s altitude, so it gets “cut off” or eclipsed.
The best passes are the ones that are overhead because the station is closest and brightest, rivaling the brilliance of Venus. But even an average pass is plenty bright and fun to watch. For tweets and short videos showing you what the ISS crew has been up to recently, click here. Wishing you clear skies!