Are stars usually visible in daylight? Can't imagine what else it could be however I have never seen that before.
Both the planet Jupiter and Venus are often visible even when the sky is becoming bright.
Venus, most noteably, is often visible in full daylight with a clear sky. When Venus is at it's maximum brightness, it still can appear as a faint daylight object if you know where to look.
Some information here:
Edited by synchronomy, 30 November 2012 - 03:55 PM.