Space shuttle Endeavour is scheduled to undock from the International Space Station on Monday, August 20th. If that happens as planned, sky watchers across North America may be able to witness something rare and beautiful: a double-spaceship transit across the night sky. US cities favored for flybys on Aug. 20th or 21st include Atlanta, Boston, Chicago, Denver, Detroit, Las Vegas, New York and Phoenix. The space station and shuttle will appear as separate, bright points of light moving in tandem. Flyby times depend on where you live.
For my location in Northern Virginia region they will appear, reach maximum height and disappear respectively at the times and in the directions below.
21:28:58 10 WNW 21:31:46 49 SW 21:32:09 45 SSW
You can find the precise times and directions for your location at www.heavens-above.com