My family and I live in North Carolina, so we are blessed to have the opportunity to spend time outside for at least nine months out of the year. We love eating outside, sitting around the fire pit, and looking at the stars. One of our favorite things to do is watching flybys of the International Space Station from our very own backyard.

For years, the International Space Station has amazed me. In our day and age, it’s common to see dozens of airplanes in the sky. But the ISS is different. There are humans living and working up there, in a man-made structure the size of a football field, that travels around the earth every 92 minutes, at a speed 25 times faster than a Boeing 747!

So what exactly is the International Space Station?

According to their Facebook page, the ISS is “…a collaboration of 15 nations working together to create a world-class, state-of-the-art orbiting research facility. The Station is much more than a world-class laboratory; it is an international human experiment.”

Not only is the ISS a laboratory for scientific research, it’s also a platform for observation of astronomical and geological interests. As we get closer and closer to deep space exploration, the International Space Station can serve as a pit-stop as we travel to Mars and interstellar destinations.

Some very cool factoids (provided by the ISS Spotter app developer, Martin van Mierloo):

HOW HIGH: The ISS is in orbit at an altitude of 390-420 kilometers or 240-260 miles. The height varies as the ISS slowly descends to earth every day. Once every few weeks a rocket boosts the ISS back into the right orbit.

HOW FAST: The ISS moves in its orbit at approximately 8 kilometers or 5 miles per second! That is 25 times faster than a Boeing 747 or 9 times the speed of a bullet. At this speed it travels around the earth in 92 minutes.

HOW BIG: The ISS including its solar panels has a length of 73 meters (239 feet) and a width of 109 meters (356 feet). That’s about the size of a soccer/football field.

HOW MANY RESIDENTS: Normally three to six people stay at the ISS. Every two to four months a new crew arrives at the ISS, replacing the old crew. When a new crew arrives they work together for a few weeks before the first crew returns to earth. The Soyuz spacecraft that delivers the crews has seats for three people.

WHY WE SEE IT: In the hours after the sun sets (or before the sun rises) the light of the sun still reflects on the solar panels of the ISS. The ISS still flies in the sunlight while down on earth it’s dark. This is the perfect time to spot the ISS. The solar panels are so big that you can see the ISS even if it’s hundreds of kilometers/miles away.

WHY WE CAN’T SEE IT: The reflection on the ISS solar panels is not bright enough to be seen against the blue sky during the day. Only a few objects such as the moon are bright enough to be seen during the day.

HOW LONG HAS IT BEEN UP THERE? The first module of the ISS (called Zarya) was launched in November 1998. Additional missions in 1999 and 2000 delivered modules and components to enable permanent residence. On November 2nd 2000 the first crew arrived. Since then there were always people at the ISS. The build of the ISS was finished in 2011.

HOW MUCH IT COST: The ISS is the most expensive man made object. Total costs are estimated at between $100 to $160 billion. It costs $3 billion per year to keep it operational.

“Mary, stop babbling about the ISS…tell us how to see it in our backyard!”

Okay, okay…I get carried away with all things science and math. So let’s get to what you really wanted to know!

Although there are a few desktop programs and mobile apps that you can use to locate the ISS, I have a clear favorite: ISS Spotter (and no, I’m not receiving any compensation for promoting this product). This app became available in May of 2012.

You can download the ISS Spotter in the App store or in Google Play.

Not only does this app come with a ton of features, it’s also FREE. No gimmicks, absolutely F R E E ! The developer, Martin van Mierllo, wants the app to be available to as many people as possible. He said the best reward is receiving emails from parents who watch the ISS with their kids (awwwww! You can send him an email here if you’d like).

The app provides you accurate and easy-to-use information on locating the International Space Station. You do not need a telescope or binoculars. You don’t even need a sextant (made you look!). The ISS Spotter apps lets you set up alarms to notify you when the ISS will be visible in your location.

There are three main pages: Position, Forecast, and Settings.

ISS Spotter Position screen.PNG — Position Screen

This screen shows you exactly where the International Space Station is located on a map. It’s extremely accurate (it updates every second), and you can see the projected path on the yellow curved line. You can zoom in and out, and toggling the Lock button on/off will focus and refocus on the ISS.

ISS Spotter Forecast screen.jpg — forecast screen

This is my favorite screen! It lists the upcoming passes of the ISS relative to your position for the next 7 days. It gives you the date and time, as well as the peak elevation (the higher the degree the easier to see, especially if you’re in a neighborhood with lots of trees) and the brightness (more stars means more clearly visible in the sky).

You can easily set an alarm by clicking on the alarm icon next to each listing.

Click on one of the listings and you will find the compass view. This is the really fun part! Look for the “START” arrow. That is the direction from which the ISS will rise from the horizon. Similarly, the “END” arrow is the direction where the ISS will disappear under the horizon line.

Note: You usually can’t see the ISS lower than 10° from the horizon.