http://blogs.discovermagazine.com/badastronomy/2010/04/06/watch-the-skies-for-the-shuttle-and-iss">Watch the skies for the Shuttle and ISS
The Space Shuttle Discovery launched successfully yesterday, and it’s on its way to the International Space Station. It will dock with ISS tomorrow, April 7.
Until then, the Orbiter has to play catch up, slowly changing its orbit until it matches the station’s. The thing is, you may be able to watch this unfold! Both the Orbiter and the ISS are easily visible to the unaided eye, and in fact the station is potentially the fourth brightest object in the sky (after the Sun, Moon, and Venus). As they approach each other, you can see them as bright(ish) 'stars' moving rapidly across the sky.