The International Space Station (ISS) spreads its wings across both evening and morning skies for northern hemisphere skywatchers this week. Normally, we see one or two passes at dusk or dawn, but twice a year around the solstice, you can see up to five successive appearances a night. Encore, encore!
The first spell happens from May 17-20. A dedicated satellite watcher will to start at dusk and stay up till dawn will see the space station on every one of its 93-minute-long orbits — four or five passes depending on your location. That’s a lot of time under the stars, but what a kick. Southern hemisphere get their turn around their summer solstice between November and January.
How it looks out the windows of the space station around the time of summer solstice. Like seeing the midnight sun in the Arctic summer, the sun never sets at the station.
Each year within a few weeks of summer solstice in either hemisphere, the space station’s orbit and the line of separating day from night on our planet (called the terminator) nearly align. For a few days and nights the Sun never sets on the ISS which means that observers on the ground see it during each orbit. Meanwhile, the astronauts on board the station orbit in continuous sunlight.
It can get dang hot up there, hour after hour in direct sunlight, so the solar arrays are angled to help shade the main body of the spacecraft. Remember that in airless space the side of you that faces the sun can become extremely hot, while your backside is very cold. With no atmosphere there’s no equalizing of temperatures, only extremes. The moon’s like that. During the long day, its surface temperature climbs to 260°F (127°C) and drops fairly quickly to –280°F (–173°) at night.
The ISS will be visible at all hours through about May 25 and then only during the evening into early June. You’ll have lots of opportunities to see it. To know when and where to look check out Heavens Above. Click the link, select your city, and then tap the ISS link for a list of passes in the coming nights. Click on a date to see a map and timeline. Or go to NASA’s Spot the Station site for times, where you can also sign up to get e-mail or text alerts whenever there’s a favorable pass for your city. Apps are great, too. Try the free ISS Spotter for iPhone and ISS Detector for Android.
A few things to know. The space station always rises from the western direction and travels east across the sky. A typical pass takes about 5 minutes but don’t be surprised if you suddenly see it fade from sight. That just means it’s moving into Earth’s shadow — essentially the ship goes into eclipse! Once in shadow it’s cut off from sunlight and disappears from view. I always encourage observers to keep a pair of binoculars handy to watch these disappearances. As it passes from sunlight to shadow, the sun “sets” at the station, causing it briefly glow reddish-orange the same way an earthly sunset colors the land and clouds orange.