There are many things to see in the night’s sky besides stars. Planets, comets, moons and human-made satellites grace us each night with their sparkling show, as well as the International Space Station, or ISS.
The International Space Station (ISS) orbits the Earth at about 17,500 mph roughly 250 miles (400km) above the Earth’s surface and is almost the size of two football pitches. It’s an orbital laboratory exploring the possibilities of science, technology and the future of the human race in space. It is probably man's greatest achievement after the Moon landings.
The ISS was built to be a space environment research laboratory and observatory, where crew members could conduct experiments in many scientific fields including biology, physics, astronomy and meteorology. It also provides valuable opportunities to test spacecraft systems and equipment and act as a staging base for possible missions to the Moon or Mars.
The ISS orbits our earth 15.5 times a day, which means the crew members on board the station experience a sunrise to sunset every 92 minutes.
The great thing is, because of the size of the ISS and its orbit, most people on the surface of our planet can see it pass over and it can even be photographed. It looks like a fast-moving plane, only much higher and travelling thousands of miles an hour faster! And it’s the third brightest object in the sky and easy to spot if you know when to look up!
Firstly, you need to know when the space station is going to be passing visibly over your location. The ISS may pass over you several times a day, but it can only be seen if the viewing conditions and orbit are right, usually at dusk or dawn (as the sky is darker and it is easier to spot). Basically the ISS is illuminated by the Sun and what you see with a visible pass is reflected sunlight, exactly the same as the Moon. The station or any other man made object orbiting the Earth has to be in the right position relative to the Sun and relative to the observer to be seen.
There are web sites such as meteorwatch.org, Heavens-above.com, twitter feeds such as @virtualastro and our personal favourite spotthestation.nasa.gov which can tell you when the ISS is passing over at your location. Information can include things such as times, maps, brightness and ground track of the station, and this info makes finding the ISS much easier.
Then look for the big dipper and follow the 2 pointer stars 5 times the distance between them until you reach the North Star and turn to it. You are now facing north.
Now, hold your arm straight out in front of you and make a fist on the horizon. The top of your fist represents 10 degrees. Now check how many degrees up you need to look according to your sighting information and there you’ll find the ISS.
When you are armed with all this information (which sounds more difficult than it actually is) you need to know what to expect to see. You won’t see the Death Star or a large spaceship with engines roaring, you are looking for a very bright and incredibly fast moving star like object. It can resemble an aircraft with landing lights on, but unlike an aeroplane there are no flashing lights on the ISS which is lit up only by reflected sunlight.
The ISS always approaches from a westerly direction and heads towards the east and can be spotted about 10 degrees or higher above the horizon. A typical pass lasts about 4—5 minutes. Very bright passes can soar straight above the observer and good photographic passes are lower/ closer to the southern horizon. The ISS will look a brilliant white colour and suddenly turn orange as it passes into Earth’s shadow and disappears from view. On some brief passes this can be overhead and an eerie sight.
The ISS is very easy to photograph, all you need is a camera capable of taking long exposures and a tripod (or something to steady your camera on). There are even apps for smart phones that will allow your device to take long exposures.
Check timings and place your camera on the tripod and take some test exposures of roughly 15—30 seconds and play with some settings to get a good bright starfield or skyscape. When the ISS passes by make sure it is in view of the camera and take the picture, you can re-position after each shot and take another – it’s that simple.
What you will get is an image with a white streak, this is the path of the ISS and some images can be very beautiful. However, if you are wanting to take close-ups, you are going to need a good telescope, a webcam and a lot of trial and error to keep up with the fast moving ISS, but it can be done.
Good Luck! And Happy ISS gazing!