I was in a grass field near lincoln park with a wide view of the night sky. i was playing fetch with my dog and i spend the time stargazing. my eyes started tracking a blinking light coming in from the west, circular in shape, it moved in a straight path. the light would emit two small blinks of a faint blue timed equally apart (1-2 seconds). i was about to dismiss this as a satellite until the third blink appeared as a white light that was brighter and bigger then the last two. it was as bright as venus in the sky but instead of circular it was saucer shaped and the cycle started all over again. i tracked its diagonal path as the object continued this sequence of blue-blue-white for about 2 minutes. the object was overhead when it disappeared from sight on the second blink of the sequence (blue).