Woo-hoo! The space station’s back in the evening sky and visible from many locations in the northern hemisphere. If you live in the central and northern U.S. or Europe, you can look forward to about two weeks of non-stop passes. Many more of us are out in the evening compared to before dawn, making this an ideal time to get acquainted with the ways of the ISS.
#1 — Like all satellites, the space station shines by reflected sunlight. It may be dark on the ground, but sunlight still reaches the spacecraft because it’s much higher up. Think of a mountain peak that still glows pink, when the land at its feet is in early darkness.
#2 — The ISS always travels from west to east because it was launched to take advantage of the Earth’s west to east rotation. Rockets launched from Cape Canaveral gain a bonus of 915 mph (1,470 kph) from Earth’s rotation. The closer a rocket launches to the equator the bigger the free speed bonus it receives. A rocket launched from either pole gains 0 mph. Not a great spot for satellite lofting!
#3 — The space station travels at 17,000 mph 258 miles high above the Earth, completing one orbit around the planet every 92 minutes. That’s why on some nights, you might see it twice — once early in evening twilight and a second time near the end of twilight before the planet’s shadow covers the sky and the ISS.
#4 — When it’s low in the sky, the station is 258 miles high and several hundred miles away, the reason it looks a little fainter when it first appears low in the western or eastern sky compared to when it’s high overhead. It’s also the same reason the brightest passes occur when the ISS passes directly overhead; at that time it’s at its minimum distance of 258 miles.
#5 — Sometimes the ISS disappears right before your eyes. This happens when it enters Earth’s shadow and gets eclipsed the way the moon does when it enters Earth’s shadow. Keep binoculars handy, and if you see the station start to fade away, point them up for a look. You’ll be able to see the spacecraft turn red in the last rays of the setting sun.
#6 — On occasion, when sunlight strikes a shiny surface of the ISS, you’ll see the spacecraft temporarily grow brighter. These are called flares. Also be on the lookout for the glowing cloud of light that accompanies the station after it makes a water dump.
Here are three places you can go to get times for ISS passes for your community:
Heavens Above – Login at the site, so it knows your location, then click the ISS link under the satellites heading. Click the date for a map showing the station’s path across the sky.
NASA’s Spot the Station – Key in your location, hit Go and you’re good.
N2YO.com – This site automatically detects your location, then presents you with a map showing its location over Earth live. You can also have it show you passes for your city.
Spaceweather Satellite Flybys – Type in your zip code and hit Go!
Here are a few passes for my region – NE Minn.- NW Wisconsin for the next few nights:
March 31 starting at 8:39 p.m. CDT. A nice, 4-minute pass across the southern sky
April 1 starting at 9:22 p.m. Just after 9:26 p.m., watch for the station to fade away as it enters Earth’s shadow in the Big Dipper
April 2 starting 8:30 p.m. high across the southern sky. A second short pass low in the NW starting at 10:07 p.m.
April 3 starting at 9:14 p.m. across the northern sky.