Even though it is a small object at a considerable distance, the ISS sometimes becomes visible to observers on earth.

The ISS orbits the earth every 92 minutes at an average altitude of 380 km. If you know where and when to look, it is actually possible to see this space vehicle when the sun reflects off of it against a dark sky.   The ISS looks like a bright star moving quickly, it is usually visible for between 2 and 5 minutes. This phenomenon occurs most frequently shortly after sunset or just before sunrise.
Until recently, predicting the position of satellites required sophisticated knowledge of the mathematics of orbiting objects.  The Internet now makes all of this information available at a number of sites.  One of the best sites is http://www.heavens-above.com, run by Chris Peat.  This excellent site is easy to use and provides data on hundreds of interesting space objects.

Once you have accessed heavens-above.com, navigating is relatively easy. Start by clicking on "Select from our database" then  choose Canada from the list provided, next enter the name of your community (Ottawa) in the search string box.  When the search is completed, click on your community (ie. Ottawa) which will take you to the main satellites page. Selecting ISS will create a data table with all the information needed to know where and when to look to see the International Space Station.  Note that the table uses a 24 hour clock.

The ISS always moves from West to East. If you are viewing in the morning you may see the ISS suddenly appear high overhead, this is because it has just moved out of the earths shadow, similarly in the evening you may witness the ISS abruptly disappearing as it moves from bright sunlight into the earth's shadow. At some times of the year the ISS is not visible at all.

Many other objects are listed at the heavens-above site including  other bright satellites and space debris such as rocket bodies.  One of the most interesting listings at the site is the Iridium Satellite series.  These satellites provide direct telephone links. Their antennae consist of flat, mirror-like surfaces that reflect bright, narrow beams of sunlight.  When viewed from earth these satellites appear like a brief, brilliant flash. The phenomenon is called an Iridium flare. Click on the Iridium Flare table for  the next available flares in your community.

More about Iridium satellites can be found at: http://www2.satellite.eu.org/sat/vsohp/iridium.html#flare

You must know the time accurately to use this information properly.   Set your watch using the precise time available at this site: http://tycho.usno.navy.mil/what.html.

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