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The BIG Reason

Music, opinions, and portfolio of Mark Eagleton, musician and web developer in Northern CA.

The International Space Station
The International Space Station on 29 May 2011 as seen from the departing Space Shuttle Endeavour during STS-134

How To Track The ISS And Watch It Fly Across The Sky

The International Space Station (ISS) is cool. It’s a multi-section science lab in low Earth orbit (about 240 miles up), constructed and manned by personal from NASA, the European Space Agency (ESA), the Russian Federal Space Agency (RKA), the Japan Aerospace Exploration Agency(JAXA) and the Canadian Space Agency (CSA). It travels at over 17,000 miles per hour, completely circling the globe every 91 minutes.

See? Cool.

What’s cooler is that you can totally see it with your naked eye. It’s about the size of a football field. It has lots of huge solar panels, and reflects the sun really well. If the sky is dark enough and the sun is shining on it (i.e. during dusk or dawn), it looks like a really bright, really fast star flying across the sky. It travels from horizon to horizon in about 5 minutes.

There are a few ways to find out when it’s coming. NASA’s website has a SkyWatch Java Applet that works in your web browser that displays real time data from Mission Control, but I find it to be a little confusing. My preferred way to keep track of the ISS is at

You’ll need to grab your latitude and longitude first. Heavens Above doesn’t do that part for you. You can get this information from If you plan on visiting this site regularly, it’s best to set up a profile. This will allow you to enter multiple observing sites and you won’t have to keep entering your coordinates. For fastest action, bookmark the login page.

There are pass predictions for lots of satellites. The ISS is the star, though, and the easiest thing to see. Once you have logged in, click the first ISS link under the Satellites heading. This will show you the upcoming visible passes in your area.

Note that times are local to your area and in 24-hour notation. If you just remember 17:00 is 5PM, you can count the rest out on your fingers.

Pay attention to the Mag. column. This stands for magnitude, and is the measure of brightness of things in the sky. The lower the number the brighter the object. A super bright ISS pass will typically be between -2.8 and -3.5, which is unmistakably easy to spot. By comparison, the sun is -26.7, a full moon is -12.7, and Venus can get up to -4.4.

When you see a predction you want to check out (note that it is sometimes visible more than once per day, it only takes it 91 minutes to complete one orbit), click it’s date and you will be taken to a page with the sky chart that will show the visible path of the space station. Note that sky charts represent what you see when you look up from the Earth, so East and West are swapped when compared to a ground map. If this is too confusing for you, a ground track plot map is also avalable from a link at the top of the page. I find the ground track to be more useful as it includes the time of the pass.

If you are quick on the draw, you can use binoculars to track the station across the sky, but it moves fast. You’ll need a steady hand. A telescope is likely out of the question.

That’s pretty much all there is to it! Get your location, set up an account, and set yourself a remender a few minutes in advance.


Once you set up an account on Heavens Above, make a shortcut to the login page on your smart phone. The next time you’re out with your friends, check the local passes and drag everyone outside to see it. Everyone will ask, so remember: it’s 240 miles high, it travels at over 17,000 MPH, it orbits the planet every 91 minutes, it takes 6 crewmen to fully staff, and will tell you who the current crew is.