Most of Southern Ontario will be witness to a rare Double Flyby tonight.

As of 8:37am EST Shuttle Discovery undocked from the International Space Station, on her final flight and is returning home for the last time.

This evening starting at approx. 6:55 pm EST a rare double Flyby will be visible as the Shuttle and the ISS will seem to be chasing each other across the Northern sky.

The Shuttle will rise above the horizon at 18:56:00 EST (look to the NW).
It will head east across the sky rising to a height of 47 Deg in the NE.

The ISS will rise above the horizon approx. 30 seconds behind the Shuttle and follow an
almost identical track across the sky rising to a height of 48 Deg in the NE.

Below is the link to the NASA satelite sighting page for Canada.
Select your province, then select the closest city to where you live.

http://spaceflight.nasa.gov/realdata/sightings/cities/skywatch.cgi?country=Canada